


Calcium

by 7PercentSolution



Series: Periodic Tales [17]
Category: Sherlock (TV)
Genre: ASD Sherlock, Case Fic, Chemistry, Other, Sensory Processing Disorder, dental angst, paternalistic Mycroft
Language: English
Status: Completed
Published: 2017-06-29
Updated: 2017-07-07
Packaged: 2018-11-21 01:59:43
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 27,080
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11347533
Author URL: https://archiveofourown.org/users/7PercentSolution/pseuds/7PercentSolution
Summary: CalciumCa 20 40.078On the periodic table in Group 2(alkaline earth metal), Calcium is a hard, silver grey metal that is the fifth most abundant element in the earth's crust (3% of the total), and an essential constituent of leaves, bones, teeth and shells. Discovered in 1808, it is named after the Latin Calix, meaning "lime". In forensic work, those facts matter to Sherlock.





	1. Chapter 1

**Author's Note:**

> Part One:  
> Calcium is part of a compound called hydroxyapatite which is what makes our bones and teeth hard. Tooth enamel is almost entirely composed of calcium phosphate (Ca5 (PO4)3 OH). It is harder than bone, but unlike bone, it cannot regenerate naturally the way bones heal.
> 
> I am posting this on Ao3 now because the incomparable J_Baillier has just posted a response to it.

"Damn it."

John looked across the table at Sherlock in astonishment, his spoon stopped mid-air, half way on its journey from his mouth back to the cereal bowl. In the nine months they'd been sharing the flat, the doctor had never heard a single swear word from the Consulting Detective.

Sherlock held aloft a piece of toast with one perfect semicircle bitten out of the middle. He worked his mouth, as if he'd suddenly tasted something horrible.

"What's wrong?" For a split second, the doctor in John worried about his flatmate choking on his breakfast.

Sherlock lifted his plate to his mouth and spat out the half-masticated bread, which landed on the plate with a surprising clink.

"Oh- was there a stone in the flour? It is wholemeal."

With a frown. Sherlock began inspecting the soggy debris he'd ejected onto the plate. "No. Something more annoying." He poked about and then plucked something from the mess and wiped it clean with his fingers, and then placed it on the newspaper that John had been reading. It gleamed gold. Sherlock sat across the table looking at it, with an odd expression on his face.

"Oh, you've popped a crown. I didn't know you had one. Give me a smile so I can see if it's noticeable from the front."

Close lipped, Sherlock ignored his request; his frown was definitely tinged with something else that John couldn't quite identify. The Consulting Detective brought his plate up close to his face and stared at the remains of his breakfast as if he were investigating a crime scene. He picked up the magnifying glass that lived on the table and used it to inspect the half-chewed debris he'd spat out. John sensed an aura of distress emanating from him.

That made him want to reassure his flatmate, so he said, "Well, at least you didn't swallow it. You'd be digging through something far worse if that happened. If you're lucky, the dentist will be able to glue it back in."

Sherlock shook his head and kept looking through the magnifying glass. A pensive sigh was followed by a muttered, "Thought so…" He pulled out something from the toast bits and dropped it alongside the gold crown. It was an off white misshapen lump. "The tooth has broken, too." Sherlock walked over to the mirror over the fireplace and tried to see, angling his head in different positions to get a view of the broken tooth that had remained behind.

John looked at the fragment on his newspaper. As broken bits of teeth went, it was pretty big. He noted the effects of Sherlock's penchant for black coffee and the occasional cigarette- the shard of tooth was discoloured- hardly a "pearly white".

"This reminds me that I need to get registered with a dentist myself. Since I left the army, this has been the longest I've gone without a clean and a check-up. By the look of that bit of tooth, so do you. Who's your dentist? "

Sherlock turned from the mirror to stare at him; "I brush my teeth regularly. This should  _not_  happen." He glared at the gold crown on the table, as if it had somehow betrayed him.

It was true. Like clockwork, Sherlock  _always_  brushed his teeth every morning. He was as fastidious about brushing as he was about shaving. John shrugged. "Brushing can only do so much. When was the last time you saw a dentist?"

"On the Charlton Place murder- surely you remember? Lestrade was sure it was the dentist brother-in-law, but I knew the moment I laid eyes on him that it was the nanny who kidnapped the kid."

John smirked. "When I said 'saw a dentist', I meant professionally."

The brunet's brow furrowed. "I was being  _professional_ ; I'm always professional on a crime scene."

That made John giggle; Sherlock's tendency to take things literally was amusing at times. "I meant, when was the last time you had an appointment with a dentist to have a clean and check-up yourself, for your  _teeth?_ "

"I don't remember."

John finally was able to recognise the peculiar expression on Sherlock's face- it was panic.  _Oh, he's got a phobia about dentists._  Just as he started to open his mouth to tease Sherlock that at long last he'd found something "normal" about the eccentric genius, Sherlock beat him to it.

"I am not going to talk about this. And you aren't either. Ever." The tall brunet then swirled his dressing gown closed and marched off down the hall. John watched in surprise as the man shut the door firmly behind him— enough to qualify as a slam.

Trying not to chuckle, John wrapped the crown and the bit of tooth in a tissue and then put them in a specimen bottle, which he carefully placed on the mantelpiece, next to the jack-knifed bills.

It was still there a week later, after two back-to-back all-absorbing cases. In the interval, he occasionally went over to the mantelpiece and shook the specimen bottle in Sherlock's presence, and got a scowl in response. John didn't see Sherlock eat much — but he had come to realise that this was the norm with the man when he was working on a case. He managed to get him to eat some scrambled egg, but the bacon and sausage went untouched, possibly because by the time Sherlock got around to eating it, the meat had gone cold. The doctor did notice the first time Sherlock took a sip from a cup of hot coffee at the yard- a quick grimace and thereafter, every cup of tea he offered at Baker Street was met with a shake of the head or an outright curt "No" without an accompanying "thank you."

By now, John was used to the man's lack of manners, but this was even worse than normal, leading him to mutter "a please and thank you might not hurt- just occasionally."

"Why waste time on stupid things like that?" Sherlock smirked. "High Functioning Sociopath, remember?"

That led John to snap back, "I'm getting the sociopath; still waiting for the high functioning bit."

The tooth must have been bothering Sherlock, if the man's mood was anything to go by. Even cold water became an issue, and John noticed that the water jug which normally lived in the fridge was being left out overnight on the counter.

The doctor started to worry about how long Sherlock would try to ignore the damaged tooth being exposed.

It was the day after the case, and Sherlock was sprawled as usual on the sofa, eyes closed. John almost hated to disturb the man, but there was no excuse. He'd avoided breakfast entirely, so the tooth must still be bothering him.

"You know that the longer you procrastinate getting the tooth fixed, the more likely it is that infection will set in. You might need a root canal."

Without a word, Sherlock got up and went into his bedroom, and once again the door was shut with more firmness than warranted. Being closed was bad enough- Sherlock had a habit of leaving the door ajar- even when he slept. To be shut at all was a signal; to be slammed was the equivalent of a shout.

John decided to go to the pub that evening; it was fish and chips night at  _The Volunteer_  and Sherlock had declined (yet again) a hot take-away meal. The pub was at the north end of Baker Street, its copper-topped bar and range of guest cask ales making it a popular haunt with the Campaign for Real Ale crowd.

An hour later, satiated by the plateful of batter-coated cod, chunky chips and mushy peas, John stopped at the pub doorway to draw in a breath of fresh air. That's when he noticed the black car parked illegally right in front of him. The front passenger door opened, and he recognised the long legged dark haired young woman who got out in one elegant move.

"Evening, Anthea."

She gave him a smile and then opened the back passenger door, gesturing him in.

"I've only had one pint. I can manage to walk home. It's not exactly far."

"Get in, Doctor Watson." Mycroft's voice came from the other side of the back seat.

John slid into the car. "I've mentioned before the existence of a marvellous new invention called the telephone; wonder why you don't seem to use one?"

Sherlock's brother gave him a sideways glance. "Phones leave trails, Doctor Watson. My brother routinely looks at yours."

 _Of course he does._ By now he knew Sherlock thought anything of John's was fair game, but the lack of privacy still annoyed him. John looked at the traffic, as the car did an illegal u-turn and proceeded fifty feet the wrong way up a one way street, presumably to avoid being seen by a certain pair of grey green eyes. Buckling his seatbelt rapidly, he muttered, "So, we're taking the scenic route." The car turned onto Allsop Place and then onto York Terrace.

Clearly, his 'kidnapping' was something that Mycroft didn't want Sherlock to know about. "I told you once before that I won't spy on Sherlock for you."

"No need to repeat yourself, but I do need your assistance regarding my brother's dental problem."

Shaking his head in disbelief, John's chin went up. "You are a bugger; I mean that literally- you must be bugging the flat if you know about his crown."

Mycroft shrugged. "It saves a lot of time. In this case, I know that he is being difficult about getting his tooth fixed, so I am going to propose a course of action. I would like your assistance, however."

"I've already tried to raise it with him- and he's not willing to even talk about it, let alone do anything. Am I right in assuming he doesn't like dentists?"

John wondered if he was imagining Mycroft's fingers tightening on the handle of his umbrella. The white knuckles suggested that not only was his guess right, but that it was the cause of some concern to Mycroft.

"You have no idea, Doctor Watson. Since his very first visit to a dentist, soon after his first tooth erupted when he was six months old, he has been impossible. Anyone who went anywhere near his mouth was greeted by a screaming tantrum; even at three he had an impressive bite, as several nannies discovered. By the time he was six and his baby teeth started to fall out, the only way our mother could get him into a dentist's office was if he was sedated. And by that I mean completely unconscious. He will not go voluntarily to get this latest problem fixed- which is why I will need your help."

John had figured out the  _odontophobia_  of his flatmate- but not its cause or extent. "Why? Did something traumatic happen in a dentist chair? What happened to make him so anxious?"

Mycroft was looking straight ahead rather than at John, and seemed to be considering his words carefully. Finally he said, "My brother has hyper-acute hearing— the drill and the high speed scaling tool are instruments of torture for him. And he doesn't like the sensation of alien things in his mouth. It's part of the challenge of getting him to eat properly. You must have realised this already, haven't you?"

Actually, John had, even though he had not put his finger on exactly why Sherlock was such a fussy eater. A number of foods that his flatmate should have liked, based on his routine takeaway choices, had been flatly refused. "Texture's all wrong, John" was the only explanation given. His lip had actually curled and his nose wrinkled at the sight of his flatmate's porridge. John defended his choice—"I like porridge, and soluble fibre is good for you. A packet of oats, milk and water, plus a microwave—it's the perfect cooked breakfast for me. I even had it in Helmand."

"Disgusting."

"To each their own" had been John's reply.

The doctor looked away from the traffic as they turned onto Marylebone Road and back at Mycroft. "So what do you propose?"

The elder Holmes reached into his suit pocket and withdrew a small plastic packet with some white powder in it. "Sedation. Administer it tomorrow morning; tasteless, odourless and undetectable, even to Sherlock's nose. Stir it into anything he's willing to drink at the moment. Once he's out, I will have him collected and delivered to the dentist. If we're lucky, he will wake up back at Baker Street, none the wiser."

John smirked. "I think the World's Only Consulting Detective will spot that his tooth has been fixed and the crown replaced."

"Of course. But such is his phobia that he will not mention it. How do you think the crown got there in the first place?"

"What is the sedative and how can you be sure about the dosage?" He was suspicious.

"Flunitrazepam. It's a water-soluble benzodiazepine, with considerable memory impairment, which in this case is exactly what he needs. He's had it before, with no side-effects. Once he's out, the crew that collects him will keep him under during transport. Just find an opportunity to put it into a glass of water; it can go into tea or coffee, if you think he is likely to take either. Better yet, extol the virtues of a whisky for pain relief. It works even better in combination with alcohol."

John thought about it. On the one hand, Sherlock's brother had experienced a lifetime of trying to deal with his brother's peculiarities, and if he thought this was the only way to get the man to a dentist, then how could he argue? On the other hand, he didn't like the idea of abetting this level of intrusion and manipulation. Flunitrazepam was also known as Rohypnol—a date rape drug. The idea of drugging Sherlock against his will made him feel decidedly uncomfortable. It was something that could undermine their developing friendship.

"Nope. Sorry, but I don't do this sort of thing- drugging someone without their permission is not legal, decent or honest. GMC guidelines are there for a reason, Mycroft; I'd lose my license over it. "

Mycroft rolled his eyes. "How very  _noble_  of you, Doctor Watson. I can assure you that there would be no consequences for you.* When my brother is screaming in pain from toothache, you are likely to change your mind. He can be utter hell to live with- in pain that becomes even worse. Call me, preferably before he reaches that state."

"He's not stupid, you know. If it gets that bad, I'll tell him about the drug, get him to agree to take it voluntarily, and then everyone wins." John had the feeling that Mycroft rarely credited Sherlock with much sense.

"I am not naïve enough to allow hope to triumph over experience." Mycroft leaned forward and touched a button. "My dear, ask Stimpson to drop the doctor off at the next corner, please. " He turned back to John, "Call me when you come to your senses about this."

The car stopped at the junction of Marylebone and Luxborough Street. John got out without a backward glance, gobsmacked that Mycroft had thought he could be suborned in this. Sedation without permission from the patient is just unethical, and that fact alone made him so annoyed with the elder Holmes that it took him a whole day to recover. Sarah wanted to know what had put him in such a bad mood, and he just shook his head.

When he got back from the clinic, Sherlock was out. John sometimes wondered what the Consulting Detective did when he went left the flat on his own. There was no case on, no visible signs of an experiment on the kitchen table. The violin case was shut, no music on the stand. His eye landed on the specimen bottle, but quickly passed over it.  _Not going there._ Sherlock was an adult, perfectly capable of deciding when he needed a dentist; it wasn't any of John's business.

He fixed himself an omelette and watched crap TV. He'd started to get into the Dragon's Den- one of the contestants had an ego to match both of the Holmes brothers. That made him smirk- he wondered if either of them could ever be practical enough to run a business. Then the smirk faded; if Sherlock was to be believed, Mycroft ran the British Government, so that must count for something.

By eleven he gave up waiting for Sherlock, and went to bed. He took a glass of water up with him, and wondered if he should get two filtration jugs. He always preferred his cold- probably a holdover from spending too many a night in the deserts of Afghanistan.

When he woke up, it was to see a stripe of strong sunlight across the wall- the curtain never seemed to completely block it out. Bleary-eyed and sleep fuddled, for a moment John wondered whether he'd had too much to drink last night. He had a headache that felt almost as if he'd had a hangover, but he'd only had a glass of whisky to keep him company on the sofa while watching  _Dragons Den_. A glance at the clock on his bedside table made John groan- he was supposed to have been at work twenty minutes ago. Sitting upright, he ignored the room spinning and stumbled to his feet, looking for his phone. He'd have to call the surgery and tell them he'd be late.

There was a text message alert, and he grimaced when he recognised Sarah's number- probably chasing him up. He thumbed it open.

**9.36am Hope you're feeling better. Keep your virus at home. Shifted appointments so you can take today and tomorrow off.**

He stared at the screen for a few seconds, trying to make sense of the text. Had Sherlock sent a message in already, saying he was unwell, so he could sleep in? John was having real trouble remembering anything at all about last night. He had a vague recollection of coming home to an empty flat and then going to bed. Right now, though, a very full bladder was demanding his attention.

The doctor fumbled his dressing gown on and went downstairs. Sherlock's coat and scarf were hanging on the hook as usual, but the living room and kitchen were empty. He wandered down the hall and stopped in the bathroom for a pee. The relief was amazing- and it made him wonder if he'd had a lot to drink. That summoned the memory of the pub… and then like a glimmer of light through his mental fog, a recollection of a conversation in the back of a car.

 _Oh shit._  He stumbled back out into the living room and opened his laptop. He had to type in his password twice, because his fingers still felt half asleep.

There in the bottom right hand corner of the screen was the time and date. And it was Thursday, not Wednesday**.

He'd lost a whole day, and he had a sneaking suspicion that he wasn't the only one.

Fuelled by anger, John marched down the corridor to Sherlock's room, knocked and opened it without waiting for an answer.

The man was sound asleep, on his side in what John immediately recognised as a recovery position. And dressed in pyjamas.

Anyone who actually knew Sherlock knew that when he finally deigned to sleep in an actual bed, he would spread out like a starfish, taking up the whole mattress. And he slept naked in his ridiculously expensive Egyptian cotton sheets. The pyjamas were only worn when he got up- as a concession to sharing the flat with another human being. And even that sometimes turned into a sheet off the bed, when he couldn't be bothered with actual clothing.

John walked over and decided that if this was what he thought it was, then the man would probably sleep through for some time yet. He lifted Sherlock's hand, found the pulse and counted.

He resisted the temptation to look in Sherlock's mouth. It was slightly ajar, and a sound somewhere between a deep breath and a snore was emerging. He decided to let sleeping consultant detectives lie and went back into the kitchen to fix some strong coffee while noting the conspicuous absence of the specimen bottle on the mantelpiece.

Two cups later, his head was clear enough to deal with the other Holmes. John turned on his phone and hit the third speed-dial number listed.

On the third ring, an urbane voice answered, "Good morning, Doctor Watson. I trust you are recovering from that bout of winter vomiting sickness?"

John stared at the phone. "You bastard. You drugged us  _both_. How the hell did you do that?"

" _Cherchez la femme_ , Doctor Watson. I asked Mrs Hudson to put it into the jug of water in your kitchen the night before last. Given that you both drank from it, Sherlock cannot now blame you. Your … _honour_  remains intact."

"Why would she do that?"

"Never underestimate the power of maternal instincts in a woman; they will always overcome scruples. Mrs Hudson thinks of you two as 'her boys'; I merely allowed her to do what had to be done to ease Sherlock's suffering."

"What drugs were involved?" This was asked through clenched teeth.

"I had a feeling you might ask that. Bear with me for a moment, while I get my notebook." A brief moment and then Mycroft started reeling off the drugs: "flunitrazepam in the water to put him to sleep, then he was dosed with ketamine during transport. When he got to the hospital, he was briefly ventilated by a bag mask, while an infusion of propofol and something called remifentanil was started. They used nasal intubation so they could get to work in his mouth. When they were done, and the anaesthetic was stopped, he started breathing on his own again. And then he was given a dose of ketamine with midazolam, with one top up of ketamine on route to Baker Street. When they got him into the bed they gave him one more dose of midazolam***. He won't remember a thing, but he will know that it's been taken care of. If you don't mention it, he won't either."

"And me? I didn't wake up, so you must have continued to drug me."

"Just the flunitrazepam to start and then midazolam- applied buccally."

"Just for the record, Mycroft, I object most strenuously to being drugged without my permission. I might have had a bad reaction to it."

There was a sniff from the other end of the phone. "Doctor Watson, I can assure you that your medical history was consulted before anything was administered. As too many medicines provoke a paradoxical reaction from Sherlock, we were  _very_  careful. Ability to impair memory was particularly important in his case. You didn't need that; hence you have more memory about the incident."

"Don't ever do this again, or I will tell him." He put his Captain's voice of authority into the words, even though he knew that it would have little effect on the elder brother's behaviour. Come to think of it,  _both_  brothers seemed to have the same attitude towards boundaries.

"In this case, you should look a gift horse in the mouth, Doctor. When you brush your teeth this morning, you will find that you've had a full cleaning and a check-up, too. I am happy to pass on the news that you are in fine dental health."

John hung up on him. There was an incoming call from Lestrade.

oOo

"It's definitely human." Molly lifted the sheet on the body, as Sherlock strode into the mortuary, with John and Detective Inspector Lestrade following close behind.

The victim had turned up rather bizarrely at a funeral home yesterday morning, delivered there at some point the night before last and left in one of the coffins on display. There were no signs of a break in, and Lestrade's team had come up with nothing in the statements from the various employees as to how a body could have been dumped quite so easily. There was nothing with her in the coffin to identify the body. The naked woman was blonde, blue eyed, of average height and weight. She had no distinguishing features— apart from one.

On the phone to Lestrade earlier that morning, Sherlock had not been enthusiastic. "What's worth getting out of bed for?"

Lestrade's answer was succinct. "You're good at this sort of thing—the weirder, the better. "

"You think that's a reason to be interested?" Sherlock's question was a rhetorical one, he didn't sound like he agreed.

The DI then added, "She's been bitten. And not by an animal. It's a message- and I need you to help me figure out what it is, who she is, and how she ended up that way."

John had encouraged Sherlock to take the case. "You're the one who's been moping for the past few days; I could do with a stretch of legs myself."

When the pathologist pulled the sheet off the corpse, John took a closer look at a set of bite marks, rather more oval than circular, with deep bruising, on the woman's left breast. He tried to imagine how it could be done- and what possible motive a person could have for such a desecration.

A rather raspy baritone elaborated on what John was seeing. "Inflicted either while she was still alive or post mortem, within a minute or two of death." Sherlock was on the other side of the mortuary trolley, examining the same wounds with his pocket magnifier. He'd been grumpy and curt ever since waking up, when he could be bothered to say anything.

"Why would someone bite a victim? What kind of motive are we looking at?" Lestrade was trying to make sense of the crime, but not making much headway.

Sherlock cleared his throat and shrugged. "Two kinds of biting- one is done in anger, using teeth as a weapon in a fight. That causes a distinctive wound pattern—lots of tearing and bruising. This bite is precise, slow and designed to leave an imprint. Biting like this is a very intimate thing; it suggests a sexual motive and that could even be the main sexual act the killer wants to perform - surprisingly few sexually motivated serial killers have intercourse with their victims or even masturbate at the scene."

Lestrade shook his head. "No sign of  _that_  in the coffin, according to the Forensic team, but we don't know where the primary crime scene was. In fact, we can't actually be sure she was murdered."

As Sherlock zeroed in on the wound, putting his face just inches from the dead woman's breast, he started a running commentary. "All thirty two teeth fully erupted- so an adult: 8 incisors, 4 canines, 8 premolars, and 12 molars, including 4 wisdom teeth."

"So, the murderer is a  _clever_  adult," John teased, looking across the body at the brunet. He was trying to use humour to get Sherlock to lighten up.

Sherlock wasn't amused. "How droll, John. They're called  _wisdom_  teeth because they are the last to emerge- usually between the ages of 17 and 25, but sometimes they don't show until much later. Mycroft's top left is impacted, gives him grief from time to time." He sounded rather pleased by the fact.

Greg sniggered, "how many wisdom teeth have you got, Sherlock?"

That provoked a sniff rather than an answer.

Helpfully, Molly offered, "Some or all of the last set of molars can remain unexposed because there isn't enough space."

"I would have thought Sherlock has a big enough mouth," Lestrade said.

"The number of wisdom teeth is not a sign of intelligence," was the baritone retort. As if to push the conversation onto safer territory, Sherlock waved in the vague direction of the pathologist. "Did you manage to swab the wound for traces of any saliva? It could provide DNA."

Molly nodded. "Of course, Sherlock, a forensic odontology course is compulsory for pathologists. There wasn't any in the bite marks. In fact, the whole area shows signs of being wiped clean with disinfectant. No traces of micro-organisms either. Not in the bite anyway. There were some under her fingernails. I've sent it for analysis."

Sherlock stood bolt upright and glared at her. "Why didn't you save them for me? I could have done that analysis better, and in half the time." His tone was decidedly peevish.

Molly looked embarrassed.

Lestrade came to Molly's defence; "Neither of you two could be bothered to answer your phone yesterday. I couldn't wait."

Sherlock sniffed, and returned to his scrutiny of the wound. "I'm assuming that the fingerprints did not match anything on the system and that no one has reported a missing person fitting this description?"

Lestrade shook his head, as Molly chipped in, "All we know is that she's been dead for anywhere between four and ten days; the rate of decomposition would depend on the temperature and humidity of where the body was kept."

"You've taken photographs of the wound?"

"Of course. They're already on the computer."

"Anything else?"

"Apart from the fact that she stopped breathing, she was in good health. No broken bones ever. No signs of any medical conditions. In fact, she was fit- good, well-defined musculature, healthy heart and lungs. She took care of herself- natural colour of her hair, nails, skin and teeth are in great shape."

Lestrade nodded, "…and pretty, too; attractive enough to catch the eye of her killer."

Molly glanced at the DI, before continuing her description. "No sign of sexual assault- or recent activity either, but she's not a virgin. She's aged between thirty and forty, I would say. No signs of pregnancy- no stretch marks, no change in nipple colour."

Sherlock looked down at the corpse. "She's been married though- for at least a decade, maybe more."

Lestrade frowned, and Molly threw a questioning look at Sherlock. "She wasn't wearing a ring when she was brought in- and there's no tan line, so how can you tell?"

Sherlock rolled his eyes, and poked at the woman's left index finger. "Look below the knuckle. The narrowness around the proximal phalanx bone is caused by a set of rings constricting the soft tissue; the superficial flexor tendon in particular gets squeezed. That only happens when a ring is worn for years. In her case, the missing tan line just means she's been divorced for at least a year."

A little tentatively, Molly asked, "Or maybe widowed?"

Sherlock snapped back, "No. Widows generally continue to wear their rings in a gesture of marital commitment, unless the marriage was a total disaster. Balance of probability is divorce." He lifted the woman's side, and peered underneath at her back and buttocks . "Recently arrived in this country."

"How the  _hell_  can you tell that?"

"She's got an all over natural tan- so not a sunbed, but spent time somewhere overseas where naturist bathing is legal. It's started to fade, so maybe here for a couple of weeks before she was killed."

"Well I suppose we can start by looking at any passport entries that match her description, but there are going to be tens of thousands. We need to narrow it down, Sherlock."

Sherlock shifted his focus to her left forearm. "She's recently had a cannula here."

The pathologist nodded. "Yes. I thought at first she was a drug addict and that it was an injection site. There are signs of nasal bleeding- mucus membranes get damaged by insufflation of drugs. But a dipstick on her bladder contents showed no positives for opiates or cocaine, so I ordered a blood test, which showed traces of midazolam, propofol and fentanyl. The murderer could have used drugs to put her out completely before he bit her. Whatever the dose, it caused her breathing to stop, which was technically the cause of death."

The doctor's eyebrows raised in surprise. "IV propofol and fentanyl are hospital anaesthetics; surely that limits who could have used them to kill her. A medical professional would know all he had to do was let the drugs suppress her breathing- that's murder. You don't need an anaesthetist to inject drugs into IVs; you need them to keep the patients alive after what those drugs do to them. Maybe the killer just took a DIY approach."

Lestrade was listening. "Maybe she's a medical tourist- you know, someone who comes here just to be able to get an operation on the NHS. And it went wrong."

"The bite, Lestrade. This isn't accidental."

"But, if it is murder, this fentanyl's hardly the sort of thing found on a street corner dealer, so we should start checking hospitals."

Still bent over the body, looking for other injection sites between her toes, Sherlock grunted.

"Don't be so sure, Lestrade. An analogue, alpha methylfentanyl's been around since the late 70's- and recently the Mexican cartels have started cutting heroin with fentanyl for a bigger kick. The street names give you a clue-  _China White_ ,  _Drop Dead_  and  _Serial Killer_ \- which tells you what you need to know about its strength. Fifty times more potent than a natural opiod, fentanyl is undetectable in a conventional urine drug test, which makes it highly attractive to the wealthy user. And even in a full immunoassay test, it's almost impossible to detect the difference between medicinal fentanyl and illegally manufactured versions- so you can make up a conceivable excuse if you are caught in a random drug test. Propofol is illegally used, too—but over ninety percent of propofol abusers are healthcare professionals, because they have access to hospital supplies, which can be sold on the street. Ketamine was also first used in hospitals, but is now readily available on the street, too."

John drew a shaky breath. Sometimes, Sherlock's encyclopaedic memory for illegal drugs worried him intensely. And the fact that he kept that knowledge meticulously up to date.

"So, why's the bite so important?"

Sherlock shrugged. "A murderer's way of marking one's territory; claiming the kill- but it can be counter-productive as Ted Bundy**** discovered."

"Okay…I'll bite. Who's Ted Bundy?"

Oblivious to John's word play, Sherlock stood upright again to throw a perplexed look at the doctor. "Really? You haven't heard of the most notorious serial killer in US history?"

John snorted. "No, can't say that information's high on my list of priorities."

Sherlock looked askance. "Ted Bundy confessed to the murder of thirty women in seven different states, all killed between 1974 and 1978, but the authorities believe that he'd murdered at least  _twice_  that number. He had a habit of returning to where he buried the bodies, performing sexual acts with the decomposing corpses."

John heard Molly's "eww" behind him.

Undaunted by her expression of disgust, Sherlock continued, "Bundy decapitated at least twelve of his victims, keeping some of the heads in his apartment. He was very clever, a law school graduate well versed in police procedure and able to avoid detection for years. When he was facing murder charges in Colorado, he managed to escape from remand prison not once but  _twice_  and went on to kill more women. Eventually, he was caught, tried and convicted for attacking four women in a fifteen minute homicidal spree at a sorority house in Florida. It was forensic dental work that was key circumstantial evidence- a bite mark on the left buttock of one of his victims matched his teeth. He was executed in January, 1989. How could you not know this?"

How Sherlock had the breath to ask that question after rattling off his long winded explanation, John would never know. "I don't make a habit of learning about serial killers, Sherlock."

Greg stifled a laugh. "We don't all have special interests that match yours, Sherlock."

This provoked a huff; "There've been  _four_ movies made about him; I'm surprised you haven't run across at least one of the films while watching your crap TV late at night, whilst bemoaning the fact that you aren't out with some woman on a date."

Before John could defend himself, the DI shifted uncomfortably. "Sherlock, get to the point. Miss Hooper says there is no sign of sexual assault; no one's mucking around with a corpse on this occasion. But if you can give us an idea where to begin, just a line of enquiry would help."

Sherlock returned to the body. He cupped his gloved hand behind her neck and tipped her head back. Opening the dead woman's mouth, he peered in, using his pocket magnifier.

" _Oh!_ "

"What?" Both John and Greg asked the question at exactly the same time.

Sherlock set the head down gently and then stepped away from the body, his hands up under his chin. Then he spun on his heel and returned to the trolley, peering at the wound again from just inches above the dead woman's breast. When he stood up again, it was with a self-satisfied smile.

"Take a look inside her mouth- all of you."

Molly grasped the corpse's jaw again, and the three of them peered in. After a few moments, they exchanged dubious glances. "What are we supposed to be seeing?"

Sherlock rolled his eyes. "Are all of you equally blind? It's obvious; the murderer is someone who is in the dental business."

"What?!" This time, John beat Lestrade to the question, but it was Molly who followed up with one of her own, "How do you know?" She let the head down and the woman's mouth closed.

Sherlock whirled back to the body and pointed to the bite marks on her breast. "Oh, for God's sake, just  _look_. The bite wound matches her teeth."

Greg's spluttered in disbelief. "Sherlock, it's a physical impossibility for her to have bitten herself like that."

Sherlock smirked. "Who said she did? What I said is that the bite marks match her teeth."

The DI raised an incredulous eyebrow. "How can you tell something like that by just looking at her teeth?"

Sherlock blanked, and then pointedly looked at both John and Molly, as if seeking confirmation that the DI was being dense. When he didn't get that reaction, he was shocked. "You  _really_  can't see it?"

"No," was the DI's answer. John shook his head. Molly just looked pained.

Lestrade blustered, "How on earth can you just look into her mouth for a couple of seconds, and then say that it's an exact match to the wound? One's a three dimensional set of teeth, the other is just a bunch of two dimensional marks."

Molly added, "Sherlock, there are thirty two teeth, and no one person's teeth exactly match another- not even identical twins; by the time they're adults, different wear patterns, dental work, even decay makes it possible to separate them. The only way an exact match can be confirmed in a court is to take a mould of her teeth, then make a cast version, injecting fast setting plaster into the mould and then put the result on the wound marks to see if it matched. That's what the forensic odontologist said."

Sherlock waved his pocket magnifier at them, dismissively. "I don't need that. I can  _see_  that they match— exactly. My spatial reasoning and object visualisations skills function well. Don't yours?"

John, Molly and Greg all gave Sherlock an uncomprehending look, which led the tall brunet to roll his eyes and mutter, "I am surrounded by idiots."

Lestrade crossed his arms and challenged him, "So, clever clogs, prove it. You'd have to if you were on a witness stand and had to convince a jury."

"Molly, have you got a piece of foil about fifteen centimetres by ten- or even better, a piece of wax that size?"

"Um…maybe some foil. Let me see." She went over to the lab bench and started rummaging in some drawers.

"What's that for?" John's curiosity was piqued.

"How dentists check a bite, once they've made a filling. It will render the three dimensions of her teeth into a two-dimensional version that I can overlay on the wound- so those of you with limited perceptual skills can understand something that is blatantly obvious to me."

"Oh, why didn't you say so? I have articulating marking paper." Molly had been listening while trying to find the foil. "I use it to help identify unknown bodies from dental records- they're easier to send to practices that don't keep photographic dental records."

"Good, I'll need a hard surface that can fit into her mouth, too."

She came back with a pair of scissors and a pad of what looked like rectangles of old fashioned carbon paper.

Sherlock tore off the back of the pad and overlaid it with a carbon sheet, before returning to the corpse. "Lift her head and open her mouth, John. I'll do the top teeth first, and then the lower."

A few minutes later, the Consulting Detective laid the sheets with the blue marks made by the woman's teeth onto her breast. The original bite wounds could be seen through the thin pink paper- and the marks aligned, exactly.

"You could really  _see_  that just by looking? How do you do that?" John's admiration shone through the questions.

Sherlock shrugged, "How is it possible that you  _cannot_  see that they match?"

Greg sighed. "So, let me get this straight. The murderer is a dentist, who takes a mould of her teeth and somehow creates a set of false teeth that he uses to bite her? Why would anyone do such a crazy thing? And how are we going to find this guy?"

"Not easily. Normally, one would send the dental information to dental practices and ask them to check their records. But the murderer is unlikely to admit that this woman was his patient, so will deny that there is a match."

"So, without a finger-print match or dental records, and with no missing person reported who matches her description…"

Molly finished the DI's statement, "…she remains a Jane Doe. There's nothing in the rest of the body that marks her out- no broken bones, no implants with a serial number that could be traced. So, there is no hope of identifying her."

"I didn't say that, did I?"

Three sets of eyes returned to the Consulting Detective, who continued, "Sometimes, it's what you  _can't_  see that is the important thing."

Greg snorted. "Okay, Sherlock- now you are just taking the mickey."

"No, I mean it- there are three obvious clues. First,  _look_  at the teeth." He waved the carbon sheets, but, when he got an uncomprehending shrug from the DI, Sherlock sighed and went back over to the corpse and tilted her jaw, theatrically pointing into the gaping mouth. "What's missing?"

Molly shrugged, "she's not missing any teeth."

He rolled his eyes. "She's  _missing_  any dental work at all. She's got  _perfect_  teeth. Not a cavity in sight, no fillings, no crowns, no implants, no sign of gingivitis or gum retreat. This is a woman who brushes, flosses and keeps her teeth in perfect condition. So why would she consent to a procedure involving conscious sedation?

"That's the second thing that's missing. No signs of struggle at all. So she was a willing participant when that venous cannula was inserted."

Greg looked at the woman's forearm. "How can you tell?"

Sherlock unbuttoned his cuff and rolled up his sleeve, revealing a similar mark on his forearm. "Because I've got one, too."

The DI looked worried. "Um, Sherlock…are you…"

Before he could finish the question, Sherlock glowered. "Of course not, I'm clean. But yesterday, when I couldn't be reached on my phone I was having dental work done- hence the needle mark. And the fact that I've had a nosebleed at some point and my throat is sore is because I was intubated nasally during the procedure. Her nosebleed suggests she had something similar."

John groaned, "Mycroft thought you wouldn't remember a thing."

"Yes, well, he's stupid like that. He still thinks I'm ten years old. Drugs can affect memory recall, but once I'm awake I can deduce what happened. And you're an idiot too if you thought I wasn't going to figure it out. Next time, I'd really rather have been given a choice than be drugged without my permission. " He glowered at John.

"Yeah, well I told him that, too. He got miffed and drugged us both."

"I hope you gave him grief for that. He's no right."

"I agree. Of course, none of it would have happened if you weren't such a wuss about getting your tooth fixed."

Sherlock looked offended. "I am  _not_  a…a wuss, whatever that is."

Lestrade stepped in; "Alright children, that's enough. You said there were three things we were missing. What else?"

Sherlock tapped his left index finger. "One- she has perfect teeth, so why go to a dentist? Two- if she has perfect teeth, why consent to have that dentist sedate her?"

"So now you're saying it wasn't a dentist?" Greg was getting seriously confused.

That got him a snort of derision. "Yes and no. It's the third thing you're missing. Most dentists in this country usually bring in a qualified anaesthetist for conscious sedation during dental treatment; he or she couldn't do the constant monitoring and a procedure like an extraction, crown or implant at the same time. So, unless our murderer has a willing accomplice, that makes a dentist unlikely. However, an oral and maxillofacial surgeon needs both a dental and medical qualification, would have access to anaesthetic, and would be able to convince someone with obviously healthy teeth to submit to a procedure."

He went to the top of the trolley and lifted the woman's head again, feeling her face with his fingertips, probing down the cheeks from her ear towards the jaw line. The he shifted the position, sweeping his fingers firmly under the jaw line toward her mouth. Then Sherlock smiled, leaving his left finger in position. He gestured to Molly, "Feel that?"

The pathologist placed her fingers on the spot as he withdrew his. "Oh, yes, yes I do feel something."

"Calculi are salivary stones, formed in the salivary glands and they block the ducts. Can be painful especially after eating when the stone blocks the normal flow of saliva. The stones are mostly calcium- but oddly a patient having them won't often show a calcium imbalance or build-up anywhere else in the body."

Molly looked mortified. "How could I have missed this? I took X-rays."

Sherlock shook his head. "Not your fault. They are usually so small that they only show up in a CT or MRI scan. And those little stones are the true cause of death."

"How?"

"Logic says that this woman went to her ex-husband for the procedure- probably because she couldn't afford to pay for it; maybe she even asked him for the money, but he refused, saying he'd do it privately. That suggests they fought over the divorce settlement, and that she left him, rather than the other way around. Once he had her unconscious in the dentist chair, he just couldn't miss the opportunity to stop her for good. Biting her with her own teeth was a way of expressing his frustration, without leaving any incriminating evidence. He'd know that because she was living overseas, if no one here filed a missing person report, he'd get away with it. Our surgeon couldn't pay for a funeral without arousing suspicions, so dumped the body in the funeral home, knowing it could not be identified."

John smirked, as Lestrade rubbed his hands over his face. "Jeez, Sherlock…all that sounds possible, but how the hell am I going to find this guy?"

"Oh, that's the easy part. Narrow it down…there are nearly five thousand dentists in London, but less than a hundred OMY surgeons, of whom a small subset specialise in salivary gland diseases." He pulled his phone out of his pocket, swiped a few times and then typed furiously. A moment later, he turned the screen to the three of them. A google style map of central London had a number of red pushpins on it. "According to the British Association of Oral and Maxillary Surgeons, there are thirteen suspects. Eliminate the unmarried ones, and find the one whose wife left him a year ago and went overseas."

Sherlock gave a triumphant smile, and John noticed that his teeth were remarkably clean.

 

**Notes for the Chapter:**

> *The UK's Medical Council is very clear; doctors are not allowed to prescribe drugs or treat friends and family, as it creates a conflict of interest. Especially without the patient's consent.   
> **The "missing Wednesday" trope is so strong in this fandom that I could not resist.  
> ***all details of the anesthesia used is due to the professional opinions of my beta and sometimes co-author, jBaillier  
> ****Ted Bundy was certainly one of the most notorious serial killers in the USA and like Sherlock I am surprised that John is unaware of him.


	2. Chapter 2

**Summary for the Chapter:**

> Calcium plays a crucial role in human biology. Deficiencies and defects in the ability to absorb and utilise calcium can have devastating medical consequences. Calcium deficit is called hypocalcemia and some of the consequences include seizures, weak bones, eye problems, and an abnormal heartbeat. Sherlock has more reason than most people to know these facts.

"Drink it."

Mrs. Allan spoke quietly but firmly, in the no-nonsense, she-who-must-be-obeyed tone of a house matron. It usually worked on most of her charges amongst the Shells* of Bradbys House.

But not this time.

William Sherlock Scott Holmes was a picture of despondency. He'd been retreating into silence over the past few days, and the matron was worried about the boy being depressed. Standing in her office, Holmes stared at the floor. The thirteen year old's arms were crossed defensively, his posture somehow both distressed and defiant.

"No."

"No,  _what_?" She made sure he heard her disapproval.

"No…  _thank you, ma'm_."

She knew that the polite phrase was being added under duress, but it was an important part of her role as mother-in-absentia that standards be maintained.

A glass of milk sat on the small table in front of the boy. Beads of condensation ran down the sides of it, to pool in a ring at its base. It was a warm day in late June and the milk had just come out of her refrigerator.

Mrs Allen was something of an institution at Bradbys**. She'd been Matron since 1983. With two boys of her own, she knew something about how to motivate sensible behaviour, using a combination of push and pull. But, Holmes was proving to be one of the most challenging boys she'd had to deal with. This was only his first term, but he'd already been in her office more than most boys did in their entire first year.

"I've seen with my own eyes the fact that you don't have any milk with your breakfast here at the house – you eat dry cereal. According to the Dining Hall staff, you've not had any milk since you arrived here nine weeks ago."

"How would they know? They serve hundreds and hundreds of boys."

She recognised deflection when she heard it. "When Rigby was your shepherd, he said you didn't like going to the lunch and dinner meals. So, I asked them to keep an eye on you. You can't deny the fact that you've lost weight since arrival."

It was true. The reason this particular conversation had become necessary was that the monthly height and weight session for the boys that she ran showed the discrepancy. The first time, she'd passed it off as the result of the boy adjusting to being away from home. But the second time it happened, she knew she had to take special measures. This wasn't home sickness, and she wasn't sure how to deal with the boy's low mood. Eating disorders were a worrying issue for adolescent boys, and she knew that pre-emptive action was better than letting something get out of hand.

Beside the glass of milk there was a set of meal cards. She'd explained that for the next month, he would need to have it stamped by the dining hall staff every day to show that he'd collected a plate with a nutritionally balanced meal for lunch and dinner- and then have it re-stamped by the staff at the clearing station to be sure that that he had actually consumed all that had been on that plate. A brief lecture and the distribution of three leaflets about the importance of nutrition and the different food groups had accompanied this ultimatum. Milk was the mainstay of the dairy group, and it was on the meal card- at least one eight ounce glass a day. He'd sighed at the card, agreeing to use it – but not to include the milk. On that he was adamant.

"I know you aren't allergic to milk."

"How do you know that?"

"I have my  _sources_. I've spoken to the housekeeper at Parham." She would normally have telephoned the mother, but in Holmes' case, she'd had to go to another person. Mrs Walters had spoken at length about the boy's "fussy eating habits". He'd clearly been indulged in those habits, and the Matron wasn't going to let him get away with it here at school. "So, tell me why you don't like milk."

"It doesn't  _agree_  with me."

"What does that mean, exactly?"

He shrugged, "makes me feel a bit sick. The texture in my mouth feels…I don't know…sort of slimy, but at the same time too wet."

"You need calcium to help you grow strong teeth and bones."

"I'm not stupid. That's why I eat broccoli and spinach, which have an abundance of calcium. Can't I go? This is getting boring."

"Milk is the best form in which to get calcium- - this is why mammals produce it for their offspring."

"Most mammals don't drink milk after they are weaned. Why should humans? Anyway, human milk is different from cow milk. Plenty of people don't have access to cow milk; it's not drunk much in China for example; a lot of Chinese are lactose intolerant."

Mrs Allen smothered a smile. Most Shells would not try to debate with her, and few would know enough to be able to argue on the basis of knowledge. Or try to dismiss her as boring. "You're not Chinese."

"Some people—not Chinese— can't digest casein and whey in milk."

Sherlock's eyes were focused on the glass of milk, as if he could somehow wish it away. The seconds ticked into a full minute of silence.

In her many years as Matron, Mrs Allen had learned to recognize an impasse.

 _Time for the secret weapon._  "Mister McGarry says you like chemistry."

The  _non-sequitur_  seemed to surprise him. Warily, he nodded.

Mrs Allan pulled out an envelope from her pocket and propped it up against the glass. "If you drink that whole glass of milk, I will let you open this. It's from him— an experiment he wants you to run." His eyes grew larger at that, and she knew she had him interested.

Holmes picked up the envelope, and saw his name in the chemistry teacher's handwriting on the envelope. He turned it over, and then over again, as if weighing the option of opening it against having to drink the detested milk. Then somehow he was spinning it between his fingers, and she was struck once again by his odd habits. He seemed to like repetitive movements. She'd caught him once spinning himself around and around on the piano stool in the house music room.

The Matron had been told by the Chemistry master how to entice him, so she reeled out the line. "It's complicated, and will take a couple of days. It's an independent research project. None of the other boys are up to it, he says."

That stopped the spinning of the envelope; it was now gripped almost possessively.

"And it will involve using equipment that we don't have here at the school. He'll have to take you to a university research lab- tomorrow. The whole experiment needs to be done tomorrow and written up the day after."

That was the real bait, according to McGarry. Tomorrow was the start of the second  _Exeat_  of the term- a free weekend, which most of the boys used to go home. Mrs Allen knew that Holmes was one of the boys who stayed at school during  _Exeats_ , along with the other pupils whose parents were overseas. She knew that Holmes had been bored witless during his first free weekend, spent most of it playing the violin in the Brady's music room.

He put the envelope down and picked up the glass. It took him a few minutes, but he managed to drain the contents. Eyes closed and with a face that betrayed the fact that he was really struggling, he managed to get it all down.

"Okay. You can open the envelope."

He tore into it and started to read:

_Tomorrow morning at 9.15 I will collect you and we will walk to the post-graduate research lab at Northwick Park Hospital. There you will have a blood sample taken and then we will use a centrifuge to produce serum for experimental purposes. We will analyse it using their atomic absorption spectrometer, to identify the calcium levels in it, and discuss with the medical researchers the consequences of different levels for the functioning of neurological pathways and muscle contraction. Between now and then, I expect you to research the differences between whole blood and blood serum, what the normal levels of calcium (both the free ionised form and the bound form) should be, and the medical consequences of hypocalcemia. For extra credit, explore what is meant by the phrase 'The calcium paradox'***. When writing the results up, I expect your report to cover the biochemical consequences of calcium deficiencies._

— _Robert McGarry_

"Oh!"

Mrs Allen was delighted to see the Holmes who left the room was in a far better mood than the one that had entered it. It might not get him to drink more milk, but it had certainly banished the blues.

 

oOooOo

"You're not a lawyer. I don't have to let you see her in private." The duty officer at Charing Cross Police Station was standing in the reception area, arms on his hips—five and a half feet tall and seemingly the same dimensions wide, an immoveable object.

John held his breath, waiting for the inevitable collision between the stocky officer and the irrepressible force that was one Consulting Detective, adamantly demanding to see a suspect in their custody.

"She got a message to me; I need to speak with her. In private."

Sergeant Willoughs shook his head. "Police procedure. She turned down a court-appointed lawyer and called someone else. Her choice, but only a lawyer has privileged access. A family member would be allowed to see her, but not without police presence."

Sherlock scowled. "She has no family member available. She's an only child; her father is in Her Majesty's Prison Belmarsh; her mother died from an overdose, and Angel called Raz who was able to reach me. ME." Rattling out that litany in one breath, he stepped to the right on his way around the officer.

Willoughs moved to block his path. "You're not a lawyer or her social worker, not looking like that. So, who are you?"

Sherlock gave him a haughty glare, "You don't recognise me?"

"We get all sorts in here, but I've not seen you here before. Are you some sort of journalist?"

Sherlock seethed. "The name is Sherlock Holmes. Don't make me call Detective Inspector Lestrade. He  _outranks_  you." The man moved a step closer and loomed over the police officer.

Willoughs wasn't intimidated. "You can call whomever you like, but you're in my manor, and I stick with the rules, so no one but a lawyer, doctor or a family member gets into see a suspect, especially not before she's been charged."

John decided to step in before the two men came to blows. "Sergeant, can we just go back to basics. Why is she here?"

Willoughs turned to look at the doctor as if seeing him for the first time. "Who are you?"

"Doctor John Watson."

"Oh, did the hospital send you?"

John answered "no" at exactly the same time as Sherlock said "yes."

The officer looked confused.

Sherlock stepped into the awkward silence. "Yes, he's the psychiatrist, sent by the hospital. And he needs to see the suspect to assess her state of mind. I need to be there to make sense of it."

Willoughs was suspicious. He pointed to John. " _You_  can go in, but you'll have to have a WPC with you, because she's a female in custody." He fixed a glare on Sherlock. " _You_  aren't going anywhere, matey, unless it's to that chair over there, to wait."

John and Sherlock had a silent argument full of meaningful glares, and John won. Getting into see the suspect was more important at the moment than Sherlock scoring points over an officer.

Nodding to the doctor, Willoughs was buzzed through by the officer on the desk, and the door shut and locked behind them. As they walked down a flight of stairs, the burly man said, "It's a bad business, Doc. I don't suppose they told you at the hospital how the victim's doing? This one hasn't said a thing, except to mouth off about being arrested. She might be a minor, can't guess her age. We don't even know her name, so if you can get any of that out of her, it would be a help."

John decided that playing along was the best option. "Well, I don't know her name either. Not her real name, that is. She's just known on the streets as Angel. I don't know how old she is. I'm just here to find out what she did."

They came to a door where a WPC was peering through a slot in the door, keeping an eye on someone. Willoughs said "five minutes" and told the WPC to go in with John as chaperone. The doctor decided to ignore the WPC, focusing his attention instead on the slight figure of the young woman in the cell. She was sitting on the hard bench built into the wall, her knees drawn up to her chest, and her head down, so that all John could see was the badly cut magenta hair that he recognised. She was wearing a pair of leggings torn at the knees and a thin top, hugging herself to keep warm. He could sense her distress from across the cell- a sharp contrast to the last time he'd spoken with her.*

"Angel."

There was a growl. "You ain't Siggy. I  _need_  Siggy."

"The police won't let him talk to you- not yet. Tell me what happened, and I'll pass on the message."

She lifted her head and he could see that she'd been crying. "Siggy's the only one who can get me out of this mess. You're not him, so go away." The words came out defiant, angry.

"You know me, Angel. I came to you at Waterloo when I was looking for Sherlock. And you found him, when he was hurt, at St Pauls Church in Covent Garden. I went with him to the hospital. I never got a chance to thank you for calling Raz and helping us find him. So, let me help now."

For a moment, the mask slipped and he saw a young woman pushed to the limit, scared, and deeply distressed.

"Did someone hurt you?"

She shook her head.

"They think I did it…that I hurt Masarah."

"Who's Ma…sarah?" He stumbled over the unfamiliar sounding name.

"The baby. I was babysitting for her mum. Sammy has to work nights on the streets, but after that she'll get wasted sometimes, but once a week she stays over at her boyfriend's doss. She lets me sleep over at the council flat, in exchange for keeping an eye on the kid."

John thought about the wisdom of any mother letting a homeless person look after their child. But if the mum was into prostitution and drug taking, maybe it wasn't so surprising.

As if she could see his thinking, Angel's face hardened. "It ain't easy. You know nothing, do ya? Sammy is a single mum; got to scrounge a livin somehow; benefits ain't enough. The kiddie has to be fed, and Sammy's stuck in that crumbling heap of a flat all day wid it screaming its head off. I'd like to put you in there for a week and see how you'd deal wid it."

John raised his hands in surrender. "This isn't about me; I'm just here to find out what happened."

Sulkily, Angel looked at the WPC standing in the corner. "It's like I says to the docs at the 'ospital. Sammy went out to earn some dosh so she could feed the meter, and she asked me in. Masarah was doing her usual howling routine in the cot and I's in the living room wid my feet up under a blanket, trying to stay warm. Anyway, I falls asleep and then when I wake up, there's no noise. So I goes to the bedroom and she's over on her side, looks like she's sleepin'. But, I don't like the look of her- she's cold. I put in a blanket in the cot, but she's all floppy when I poke her, won' wake up properly. I got scared so I goes next door to the neighbour, and they call the ambulance."

"They take me wid the kid, and when we get there, they's fussing over Masarah. There's this woman asking me questions. I'm getting scared because the kid ain't waking up. I have no idea how to get Sammy- she don' have a phone, but the woman's just bleating in me ear – on-an-on about it. The docs are saying that Masarah's got all these broken bones. They keep asking 'did I shake the baby, cos she was crying too much'. I tells them no, I wouldn't do that; I didn't even pick her up. She's always been a cranky kid, crying, never sleeping right- I'm used to it. The noise don't stop me from liking her- poor mite's got a tough enough life, you know. Then I'm pushed out of the room and the coppers show up and bring me 'ere."

She glared at the WPC in the corner. "And then this lot gets going on me, asking me if anyone else was there, can anyone prove that I didn't shake her, telling me it must have been something I did, kids' bones don't just break themselves. Was I covering up for someone? Did the mum do it; who was I protecting?" Her voice had been rising through the litany of questions. "I just  _don't know!_ I was alone wid her, butI didn't  _touch_   _her_!"

The anger that had been driving her explanation petered out. "Do you know how Masarah is? No one will tell me." Angel whispered, "Please tell me she's okay."

John saw her fear, and wished he had some way to reassure her. "I don't know, but I'll try to find out. In the meantime, I'll pass all this onto Sherlock, and we'll start looking into it."

The WPC behind him shifted her weight and her shoes creaked in the silence. "Sorry, Doc; time's up."

Angel's pleading eyes followed him out of the cell.

When he got to the reception area, Sherlock was pacing. A single look at John and his face hardened. Before he could say what had happened, the door opened again and Sergeant Willoughs came out.

"Just heard from the Emergency Department. The baby died. I'm charging the suspect with manslaughter, might throw in murder for good measure. We've issued a warrant for the mum, too- she might be in on it. Once the one we've got in custody has agreed to see a brief, you can talk to her- but only with police in attendance and with statements on the record. No way am I going to mess up on procedure- too many agencies involved in this exercise, and every step of the way has to be documented. Baby killing is sure to attract publicity."

Sherlock blinked rapidly and then blurted out, "Where's the body?"

Willoughs looked startled at the question. "The hospital mortuary, I guess. St Thomas— they've got a special kid's area in their Emergency Department; that's where the constable arrested her for child abuse."

Sherlock was already on his phone by the time he got out the door of the police station. "Lestrade— you're volunteering for this one. And get the body moved to Barts, immediately. I know that this is a SUDI, and the Home Office Pathologist works out of there. He's an idiot. Molly's the only one I trust to do the autopsy right- and she'll do the preliminaries tonight, before he gets into work tomorrow. Get her to call me before she starts." Whatever the DI might have said on the other end, it was cut off, because Sherlock shoved his phone back in his pocket.

"What's a…S.U.D.I.?" John was a little lost.

"Sudden Unexplained Death in Infancy."

"How do you know about it? Have you done a case like this before?"

"Yes." This was tersely said as Sherlock strode off down Agar Street, crossed the pedestrian plaza and flagged down a cab on the Strand.

John decided that he'd wait until the man had calmed down before telling him the details. Over the past months, he'd come to know when Sherlock was more wound up than normal, and this was definitely one of those occasions.

In the back of the cab, the atmosphere was tense, but John waited. They'd gone around Trafalgar Square and up Cockspur Street before Sherlock spoke. "People always assume the worst, if a suspect is homeless— even you, John."

The doctor looked out the window at the traffic; car lights going up Regent Street competed with the brightly lit shop windows of London's premier shopping avenue. "Well, it's not looking good, Sherlock. Angel was baby-sitting, and the baby ended up dead, with traumatic injuries."

"Angel would not kill a baby."

John sighed. "I thought you're the one who says you don't have theories until you've got all the facts."

"We don't have all the facts. But one fact I do have is that I know the suspect, and she would not kill an infant."

John was surprised at the man's vehemence. It wasn't like him to be so…well, almost emotionally sure of someone's innocence.

"How do you know that? How well do you really know her?"

While John was waiting for an answer, the taxi turned left at Oxford Circus. There were a surprising number of pedestrians on the pavements for such a late hour. The taxi driver slammed on his brakes as a group of young women dressed in short dresses and high heels staggered into the street. "Watch where you're going, ladies," he bawled out of the open window. As the cab moved on, John heard him over the intercom muttering. "Not ladies- more like sluts. Too much money, too few clothes on, too much drink—worse than the boys, if you ask me."

"I didn't ask you," snapped a baritone voice. "Switch off the intercom."

He didn't speak for the rest of the journey home, but John could feel Sherlock seething in anger beside him. When the cab drew up outside Baker Street, Sherlock was out of the door before the cab had even stopped moving, leaving John to pay the driver. He didn't include a tip – no reason to reward misogyny.

By the time John got up the stairs, Sherlock was on the phone, talking in one of his imperious tones, which rather reminded the doctor of Mycroft.

"I don't expect you to roust your pathologist out of bed at this hour, just make sure he knows that Miss Hooper is authorised to undertake the initial work. The hospital would have already informed the Coronor, as part of the protocol."

He paced, while listening to whomever was on the other end of the phone. Then Sherlock stopped, and rolled his eyes.

"Because I said so, that's why. And if you'd rather your immediate superior didn't find out about where you were when you took this call, then you will do as I say."

Sherlock listened for a few seconds, then said brusquely, "Good night" before ending the call, and tossing the phone onto the chair where he'd ditched his coat and scarf. He resumed pacing, each step conveying the anger that seemed to be pouring off him. He was muttering, under his breath. "LSCB are useless."

"What's LSCB?" John asked curiously.

"London Safeguarding Children Board. Every unexpected death in childhood gets reported to them. They set up a Child Death Overview Panel."

"How do you know all this?"

"Previous case. Before your time."

"Oh…"

John decided he needed to calm things down, so he went to the kitchen and busied himself making a cup of tea for them both. While waiting for the kettle to boil, he wondered what it was that was working his flatmate up so much. It took a lot to get Sherlock angry. Annoyed, irritated, piqued, pouting- those things happened regularly. But real rage was rare.

When he carried both cups in, Sherlock was standing with his back to the room, looking out the window. John set Sherlock's cup down on the table and stood, blowing across the top of his, in the hope of cooling it down enough to drink. "So, are you going to tell me?" John said this quietly, almost making it a rhetorical.

"What?"

"Why you're so angry, for starters. Secondly, how you know Angel, and thirdly, why you're so convinced she couldn't have done this."

"I didn't say  _couldn't,_ John. Of course, she is capable- most adults are perfectly capable of killing a baby. I said, she  _wouldn't._ That's two different things."

Splitting hairs wasn't something John wanted to do; he needed to know the answers to his questions, and wondered if this was deflection on Sherlock's part. So, he waited, hoping it was clear that he was not content with this answer.

John had a sip of tea and then said gently, "pardon my grammar, but that doesn't answer the question. Why are you angry and how can you be so sure?"

"How can you  _not_  be angry?" This was growled as Sherlock turned from the window. "A young girl is accused of murder, simply because she was there. No witnesses, no investigation, just a 'let's-jump-to-the-easy-conclusion' because she is a young, homeless girl left in charge of a baby who is the offspring of a drug using prostitute who lives in a council flat. I mean, really, nothing good ever comes from  _people like that_." The last phrase was uttered with the patrician sneer that reminded John of public school snobs, the privileged classes- echoes of Mycroft swirled in the undercurrent of the tone he'd delivered it in.

"Maybe you're right, but there are precedents. Mothers who are living in poverty, lacking in education and a decent support network… and teenagers with little experience of child care…they can all get stressed by crying babies, shake them to make them stop, because they have no idea what it can do to the baby's brain. It  _has_ happened. Baby P and the Climbiè case come to mind. You can't deny that."

"There are so many wrong assumptions made in that statement that I won't even dignify it with an answer."

"Whoa- just hold on a moment." John heard the defensiveness in his tone, but wasn't going to let Sherlock belittle his comment. "The papers have been full of stories… a baby's bones don't break just by themselves. If she didn't touch the baby, then someone must have. She said she was asleep; maybe someone broke in and battered the kid because it was crying."

Then he stopped, as his brain caught up with what Sherlock had said. "How do you know that Angel was babysitting for a prostitute? You weren't in the room when she told me."

"I know Angel, and I know Sammy. Six years ago, I knew them both because they were both homeless and living on the streets, at the same time I was. Those two are close friends. And I'd heard that Sammy got a flat in the Heygate Estate near Elephant and Castle, after she had a baby. It wasn't difficult to put two and two together, when that idiot came out and said the baby had died."

"Oh…" John was surprised. "I didn't know that you kept up with the people in your Homeless Network… to that degree."

"You know nothing, John."

The doctor heard it as the echo of Angel's earlier comment. "Then enlighten me."

"You think of the Homeless Network as if they're my version of Mycroft's minions or Lestrade's informers- people paid to do my bidding or pass me information. They are people, John, individuals who have their reasons for being where they are. Most of them are there by choice, even if it is a reluctant one, because a better lifestyle is just not possible. My relationship with the individuals I know in those circumstances was and is built on trust. I'm not going to tell you the details of Angel's story- that would be a violation of that trust. But I  _will_  tell you that she'd never, ever do that to a baby, any baby, least of all to Sammy's baby."

John drew a deep breath. "Then what do we do next?"

"I'll have to prove her innocence, because unfortunately in her situation, she will be seen as guilty until it is proven otherwise. Even the law discriminates unfairly, no matter what people say. Prejudice and bigotry are as rife in the judicial system as they are in the healthcare sector, as your initial assumption just demonstrated. It is a sad fact that there are more prosecutions against people whose only crimes are poverty, lack of education, or poor life choices."

"How? The evidence is a dead baby, and we only have Angel's word to say that she didn't do it."

Before Sherlock could answer, his phone chirped from inside his pocket. He pulled it out, checked the caller ID, and then answered. "Are you about to start? Let me put you on speaker."

He let the phone drop from his ear, swiped and then Molly's voice came on. "Yes, Sherlock; Lestrade got them to move her here tonight from St Thomas. I've got the notes- they took post mortem swabs— nasopharyrigeal aspirate and pharyngeal— in the Emergency Department- they've gone off to be checked for virus and other infections. They did a Guthrie Card, too, to check for inherited metabolic diseases. And they took a lumbar puncture, also blood samples. I've been sent the notes of an external examination that was done by the doctor at St Thomas who's been appointed Designated Paediatrician, too. According to him, the preliminary cause of death was multiple broken bones and associated internal bleeding. They've sent me some X-rays through the hospital system."

"Don't wait for us to get started. Look for old fractures as well as the new. Every bone, every single one, Molly. They'll have not done bone density, so get one done, followed by a long bone biopsy. Run your own full blood serum test for calcium, phosphorus, magnesium levels."

"The standard blood test done by the SUDI protocol checks for copper, calcium, glucose, all the obvious stuff…oh, and illicit drugs. I know how to do my job, Sherlock. I don't need reminding." John heard a hint of exasperation in Molly's tone of voice.

"You're looking for reasons  _other_  than child abuse." Sherlock stared straight at John as he said that into the phone. "Babies' bones  _can_  break on their own- something as simple as falling over in a cot when they are trying to sit up can break bones, if there are underlying medical issues. Think  _osteogenesis imperfecta;_ in its milder forms, it's often mistaken for child abuse. Calcium deficiencies can also explain the problem."

"Sherlock, you know there are specialist paediatric pathologists; I've been trained and I am authorised to start the autopsy, but the Home Office pathologist will have to complete it and he will tomorrow, with the help of a specialist. So, if you are going to question my judgment, then maybe you should talk to them, and leave me out of this."

He snapped back. "No. They'd be pre-conditioned to see things in a certain way, make too many assumptions. You'll be more independent. I  _trust_  you. I'll come to Barts. John, you should come, too; we'll need your differential diagnostic skills."

"Sherlock, I'm not an expert in paediatrics—far from it."

"Doesn't matter. We need to rule out  _pyknodysostosis_ , Hajdu-Cheyney syndrome and Gorham's disease. They all have symptoms in common with  _osteogenesis imperfecta_. Those are all genetic conditions- not tested by the standard Guthrie Card, but the infant could have just been suffering from a severe calcium deficiency. Molly, to really dig deep, you'll need a urine sample. Because we need to know levels of PTH, concentrations of serotonin, GABA, dopamine and acetylcholine- all can be compromised by hypocalcemia, and could be a factor in her death. And we need to find out what the levels are for glutamate and vitamin B6. The whole lot needs HPLC-MS, high performance liquid chromatography tests with mass spectrometry with triple quadrupole."

"Sherlock- that's a very complex set of tests."

"Yes." He looked at the phone oddly, as if the pathologist has said something ridiculous.

"Um…they're  _expensive_  tests. I'll have to be sure they are needed."

"Is the truth too expensive? Is someone going to be convicted of murder because it was cheaper to be skinflints on the diagnostics and to assume they are lying?" That tinge of anger John heard earlier had flared back into life in Sherlock's tone.

"Let's just take this one step at a time. I'll start with the native X-ray images. And I can finesse a CT scan; the radiographer owes me a favour- I look after his cats when he goes on holiday."

Once the pair got to Barts, Sherlock disappeared upstairs and left John to find Molly. A few minutes later, he joined them in the mortuary, lugging a large soft sided bag, from which he produced two screens- each one looking like a computer screen, only portrait oriented rather than landscape. He commandeered Molly's lab bench, setting the screens up side by side, and cabled them one to another.

"Where did those come from?" Molly looked worried. "If it's from what I think it is…"

As Sherlock pulled out another USB cable from the bag, he explained "If it's good enough for the professor of radiology, it's good enough for us. I've borrowed them- he's hardly going to miss his thirty inch Picture Archiving and Communication System with 6 megapixel backlit display screens at this hour, is he? This way we can actually see more of the X-ray images at a time and in higher resolution. Why should they go to waste upstairs when they could be used to save an innocent suspect?"

"We didn't have these out in Afghanistan. Why do we need them?" John was curious.

Sherlock plugged it into the back of Molly's PC. "Because I need to  _observe_ , as well as see." He stood back and admired the view as the two large screens came alive.

"Right, Molly; tell us what you've found so far."

Quietly, but with authority, she said, "Female infant, aged approximately five months, as indicated by the state of the fontanelles. That surprised me a bit. Her weight is low for that age; I'd have put her at ten to twelve weeks. But, the posterior fontanelle is closed, which generally happens around three months after birth. The phenoidal fontanelle closes around 6 months after birth- and it's still just barely open, so, she's not quite there yet, but not far. That said, even the posterior one feels a little soft, the suture hasn't ossified completely." She drew breath and then continued. "There are six broken bones- four of which are posterior ribs, and the distal radius and ulna. There was a bit of bruising on her left hip and buttock, too; that's unusual in a baby too young to walk, crawl or stand."

"Sherlock…um…I've taken the blood samples for the genetic conditions and the urine sample that will show us the levels of hormones and neurotransmitters. But, I can't order the tests until I know they are needed. Even if I did, you couldn't expect them to start tonight- it's just a skeleton crew up there and they have to prioritise the emergencies and trauma admissions. Pathology is always back of the queue, because the dead don't mind waiting. Some of the tests you think are important will take longer- a lot longer."

Sherlock frowned, "Surely, the sooner you order them, the quicker we will get them. Why delay?"

Molly looked uncomfortable. "You know I'm going to have to be able to justify these tests? The Home Office Pathologist will have to stand in a Coronor's Court and present these findings- and to explain my reasons for doing the tests. There are strict protocols that need to be observed in the death of a child. Because this is a formal procedure, it just has to be done by the book. If there's a prosecution, I may have to be in crown court justifying every step I took. It can't just be ‘because _Sherlock Holmes asked me to._ ’” She crossed her arms firmly and looked up at him.

He glowered. "If you are that concerned, then let the Home Office Pathologist earn his exorbitant salary- start the tests tomorrow. But, tonight, I need answers."

Molly sighed. "I can justify the CT, a bone density scan and a bone biopsy. We've been allowed to make a start tonight, and those are within my remit. That, together with the St Thomas's blood test results when they come through and the radiographs that have been sent- well there is more than enough material here to keep us busy." She gave them both a tentative smile, "Looks like we're in for an all-nighter."

"Whatever it takes, we'll do it." Sherlock's determination was like pure adrenaline; John nodded, his own tiredness banished by the thought of Angel stuck in that cell, fearing the worst.

The pathologist called up a series of images on her PC, and then split them onto the PACS screens. "These are the radiograph images. The full skeletal survey required in an unexplained death of a baby will be looked at tomorrow by the paeds radiologist, but we can look at them tonight."

Sherlock interjected, "What colour were the sclera of the baby's eyes? Was there a blue tinge?"

Molly looked first startled by the non-sequitur and then sceptical. "She's a bit too old for that. Lots of neonates have blue-tinged sclera; they all do when they are first born, but she shouldn't have by five months." She returned to the trolley with the baby's body and with her gloved right hand she pulled up a tiny eyelid. "No, looks normal to me. What do you think, John?"

He peered at the white of the baby's brown eye. "Yep, nothing odd there." Except, of course, for John the whole experience of looking at a dead baby in the mortuary felt distinctly odd. His paeds rotation at medical school involved  _live_  versions.

"Hmmm." The Consulting Detective. "Blue sclera are a sign of infantile  _osteogenesis imperfecta_. Doesn't always show up, though." Sherlock waved at Molly, "Pray continue."

When the set of lateral X-rays of the baby's head and neck went up on the locker door, Sherlock shook his head. "No skull fracture, no neck fracture."

John looked puzzled, turning away from the digital imaging of the baby's rib cage, which showed a number of fractures on the back. "What are you looking for?"

Molly answered, "Shaken baby syndrome or abusive head trauma. But the CT showed no signs of swelling or bleeding in the brain. And I've looked with the ophthalmoscope and taken retinal photography, but there's no evidence of retinal vascular occlusion or haemorrhage, which happens in most cases of SBS."

Sherlock was looking at the X ray of the baby's lumber spine area. "Molly, can you call up the CT scan of this area?"

She tapped in some commands on her keyboard and an image came up beside the X-ray Sherlock was looking at. Molly came over to look at it, just as John pointed out "That's a transverse process fracture- and it's not visible on the plain radiograph."

Molly shook her head. "Sixty percent of transverse process fractures get missed unless you do a CT scan. Good call, Sherlock. And it's interesting, because the more usual place for this sort of fracture in a child abuse case is in the cervical area. But her neck and skull are fine."

Sherlock's shoulders seemed to relax a bit as he looked at the images. "John, what do you see; what patterns are there in the breakages?"

John had looked at a lot of X-rays in his time as an army surgeon. "Well, I'm not a paediatrician. In an adult male, I'd say these aren't rotational injuries. They look like longitudinal breaks, more consistent with a fall than a fight."

Molly wasn't so sure. "The carer could have dropped her. It doesn't mean anything other than she wasn't shaken." She turned to an image of the baby's left arm bones. "Look- here's evidence of a healed break in the right radius…" and then pointed to another image below on the other screen, "…here's another one in her foot." She grabbed a magnifying glass to look more closely. "This could be a pattern of abuse, over months."

Sherlock was using his pocket magnifier on a view of the baby's clavicle he'd just blue-tacked to the door. "Molly, I need this one in more detail, can you zoom in?"

"Sherlock, it was the  _right_ clavicle that she broke."

"I know, but I think there is something even more interesting on the left clavicle."

She found the image and expanded it to fill the screen. Sherlock leaned in and pointed to a section, exclaiming triumphantly, "Look at  _this_!"

John zeroed in on the place. It wasn't a new break. The bone must have been broken some time ago and not been set properly, so it had healed with a slight twist in it. "This could have been there since birth- it's the sort of injury that happens in a rough passage through the birth canal; the shoulders get stuck. It would have been painful for the baby—puts pressure on the joint with the scapula."

The pathologist was shaking her head. "How could an obstetrician or midwife have missed this level of injury?"

Sherlock snapped his magnifier closed. "Don't assume that she was born at a hospital. I'll have to check; it's quite possible that the birth was never even formally registered."

John thought about social workers, home visits- all the benefits that were often taken for granted but which a lot of homeless people never claimed. And that brought something else to mind. "Wait a minute, Sherlock. Wouldn't the mother need a birth certificate for the baby, to qualify for council housing? Angel said she was in a flat."

Molly asked, "Who's Angel? The mother?"

John answered. "The babysitter. According to her, Sammy is the mother of the baby, whose name is… or rather  _was,_ Masarah."

Sherlock blinked and drew a breath. "Masarah means  _delight_ or  _joy_ , in Arabic." He gave the second vowel a more guttural sound than Angel had, surprising John. Did Sherlock speak Arabic?

"Her mother Sameh is a refugee from Fallujah, in Iraq. Her family was massacred in 2003; she came into this country illegally. That experience is not going to make it easy for her to trust authorities. But after the child was born, she must have decided for the child's sake to come out of hiding. By then, she'd have earned enough to be able to buy forged documents, good enough to pass muster with a bored council housing officer. If she was smart, she'd say that the husband was dead, back in Iraq. As a single mother, she'd get priority on the housing list. But, it would have taken a lot of courage on her part to get that far out of the shadows."

"That might explain why she's not showed up yet. Too scared?"

Sherlock nodded. "Most likely. As I said, she'd be very wary of the police. With the flat cordoned off as a crime scene, and the police stomping around the estate asking questions and trying to find her, she's probably gone to ground somewhere."

Molly looked distressed. "You  _knew_  the baby? The babysitter, and her mother? Oh, how awful."

Sherlock's brow wrinkled. "What does that matter? How does my knowing a person make any difference to the facts? A child is dead, a babysitter is wrongly accused, and the mother has no idea what's happened. When she comes home, she'll find police waiting at the flat." No sooner were the words out of his mouth than he took two steps back, away from the monitors. "Oh!"

"What is it?" John knew the tell-tale sign of a connection being drawn.

The Consulting Detective grabbed his coat and scarf, and was out of the double doors in a flash. John tore after him and caught up just as Sherlock started up the stairs. The brunet turned and said, "Stay here, John. You and Molly need to wait for the test results to come back and sort out how the baby died. You're a doctor, diagnostics is what you  _do._ "

"And what are  _you_  going to do?"

"I'm going hunting, to find a missing person or two."

Five hours, twelve minutes and too many coffees later, Molly and John were narrowing things down. The blood tests had come back from St Thomas's hospital- severe hypocalcaemia was confirmed as the reason for the baby girl's fragile bones.

"This was an accident waiting to happen."

The pathologist nodded. "The hypocalcemia isn't new. The bone density test showed real issues that have been there since before she was born. The biopsy I did on her femur is conclusive. The bone cortex is way thinner and more porous than it should be. The trabecular bone tissue just isn't interconnected enough to provide the required internal bracing. It's a miracle that she hadn't broken just about every long bone in her body. With bones this weak, a break could happen anytime- when she sat up, or tried to stand. Nobody else needed to be in the room."

John rubbed his lip, "Sherlock's right, you know. If we hadn't known to look for this, the prosecution would blame either the babysitter or the mum for these injuries."

Molly had been getting quieter as the night wore on. It wasn't just the work after a long day in the mortuary; the findings were wearing her down, too.

"I keep thinking about the poor thing being in such pain, and no one knowing why. These breaks must have been excruciating from birth, but the baby had no way of telling anyone about it. No wonder she's underweight for her age. Why didn't the mother take her to a doctor?"

John nodded, remembering how Angel said the baby had cried all the time. "Maybe fear? Given that she's an illegal on dodgy documentation, maybe she was terrified that she'd get deported, so just kept a low profile."

The pathologist put the sternum saw into the sterilising cabinet. "What a sad way to die. The broken clavicle is what did her in. The calcium deficiency made the bone very brittle; when it snapped into pieces, a shard nicked a tiny hole in the cephalic vein. She died from internal bleeding, probably about ninety minutes after the break. It might even have clotted in a normal baby, but the hypocalcaemia affected her clotting capability."

"Should I call Sherlock and tell him?"

No sooner were the words out of his mouth than the phone in his pocket rang. He pulled it out and glanced at caller ID— a text from Sherlock. "Speak of the devil…"

John showed her the message:

**06.15 Come to NSY NOW. Interviews underway- sitter, mother, and father of victim. Bring medical evidence. SH**

He smiled. "That means you can go home, Molly. You've done more than your fair share tonight. I'm just sorry the tests took so long."

She shook her head. "I don't mind, as long as justice is done. He was right. I don't know  _how_  he knew, but he did. If we had gone on just the evidence of the bone breaks, who knows what would have happened to the people who cared for her?"

By the time John got to the Yard, Sherlock and Lestrade were finishing up the interview with Angel. Sally let him into the viewing room; the detective sergeant looked tired. "Glad to see you, Doctor Watson. He's been asking a whole load of questions that don't relate to abuse, and the Guv is getting a little fed up with it."

John was pleased to see another person sitting alongside Angel, presumably a court-appointed solicitor. And the magenta-haired young woman appeared to have been crying.

The DI's back was to the window through which John was watching, but he could tell that Lestrade was playing the tough cop routine.

"You've been babysitting for how long—since she was born? And the mum's been out every night, turning tricks and getting high. When did you notice that the baby had injuries? Did you ever see her smack the kid, to get it to shut up?

"No. Never. Sammy's not like that. Oh, fuck…it's gonna break her heart when she hear's the baby's dead." Angel glared at the DI. "Don't you go shoutin at her. She's scared of people like you. The stories she tells about what happened back in…" She stopped, shutting her mouth suddenly. "I ain't saying anything. I won't give you anything to use against her. S'not fair; she's had so much shit to deal wid in her life."

Sherlock took a different tack. Calmly, quietly, he asked, "Tell us about what Masarah was like as a baby. Did she have troubles feeding? Sleeping? Did her muscles twitch when she was lying down?"

"Yeah, all of that. Sammy has no breast milk; baby had formula from the get go, but I swear she spit up at least half of it, had to make do with sugary water at times. Costs money she didn't have, made her go back on the streets. And the baby cried  _all_  the bloody time. Drove poor Sammy mad with it all, worrying about her."

Lestrade leaned forward and pointed an accusing finger at Angel; he looked tired, too. "So, why didn't you tell her to take the baby to a doctor? If you thought the child was in trouble, you should have called social services."

Angel just laughed in his face. "Get real. The  _Social_? Like they's gonna do anything right? I've had me fill with that lot.  _They made me go home_ , when they knew my stepdad would beat the shit out of me. I tol Sammy not to go anywhere near 'em. Take the kiddie away from Sammy's wot they'd do. That baby was all that was keeping her mum sane. If they'd taken her away, Sammy wod a topped herself an all- gone out in one big push of H. Not like she had much to live for, if it weren't for the kiddie. She says the baby is the reason the boyfriend sticks around."

The DI butted in. "Sammy was high then, around the kid. How often did you see her and the baby together when she was high?"

Angel just shook her head. "Never. I knows you want her to be off her face around Masarah; then you could take the kid away. But, she wasn't—never. She only did heroin to deal with what she had to get up to on the streets. She's a Muslim; said that doing stuff like wot she 'ad to do would have brought so much shame on her family that she wos glad they're dead. She never got high around the baby. She  _loved_  that baby. Spent nearly every penny she earned on her, trying to keep the cot clean and all. Sammy said she was sick sometimes, but she never wanted for nothing. Baby wipes, diapers, clean clothes. Sammy was kinda…well, keen on hygiene and all that; said I wasn't to pick her up, cuddle her or anything. Made me always wash; was afraid I'd bring in something from the streets."

"So, you're saying that you never saw Sameh Ali Nasser hurt her daughter?"

"Corse not. She loves her; wot kinda idiot are you? She wanted to get off the drugs and all for her, was trying to find a programme that weren't too fussy about her papers."

"What can you tell us about the father of the baby?"

Warily, Angel glanced over at Sherlock, before returning her eyes to the DI. "Why do you wanna know?"

The Consulting Detective gave her a reassuring smile. "It's alright, Angel. I found him and he agreed to come in, with Sammy. He's next door, and he's okay with this."

Angel nodded. "Okay….that's awright then." She took a deep breath, letting it out slowly.

"Nizar's a good guy. He wants Sammy to get clean. He gis her wot he can from his wages. 'e's a cleaner working on the tube trains- nights an all. Not got much; only been here for a few years. He's legal and all, got asylum cos he was wid the Brits in Basra. He wants to marry Sammy. But, she's holding off cos she's scared that if they gets married, she'll lose the flat. She only got it cos she was a single mum. Nizar lives in a squat, wid about ten other blokes."

Sherlock nodded. "For the record, the father's name is Nizar Hussein Al Jamil, and the baby Masarah is his daughter. Detective Inspector Lestrade, we need to interview him next and then Sameh Ali Nasser." He started to get up from the chair.

"Just hold on a minute, Sherlock. I'm not done here." Lestrade returned to Angel. "Did you ever see Nazir at the flat? Did Sammy ever say he spent time there with his child? Alone?"

Angel shook her head vigorously. "No way. Sammy's too scared of the Council seeing. If there is a husband or a father, she'd lose her benefit and the flat; they'd try to get the guy to pay up something, and then cut what they gave her. So, she never let him see her. He'd hang around the park sometimes before he went off to work, just so he could see Masarah. But Sammy wouldn't talk to him, wouldn't let him be seen in public with the baby. You don't get it, do you? In Iraq, she'd be killed for this, having a baby when she ain't married. She's just scared, real scared- of  _everybody_."

"Where does Sammy go to meet him then? You said, she went to see him, spent the night—that's why she got you to babysit for her. How does she do this if there are ten blokes in the squat?" John could hear the suspicion in Lestrade's question.

"Yeah, well, TfL ain't slave drivers, are they? They gis him a night off once a week. And at the squat he shares a single room wid another bloke that does night shifts as a security guard once a week. So, Sammy & Nazir hook up and I sleep over at the flat. I don mind; she gets worried about me out in the cold, sleeping rough, so she stays over to give me a chance to kip all night at Heygate."

"If she's so generous, why doesn't she ask you to move in with her? Wouldn't she want a live-in baby sitter? You'd be off the streets and then she could get a proper job."

Angel rolled her eyes. "You know nothing. She's got no work papers. Who's going to give her a job on the black that pays what she can make on the street? She's scared if the council finds out she's out nights, leaving the kid on its own, Masarah will get taken into care. So I'm to tell anyone who gets nosey that I'm the child minder. Can't tell em I stay, though; she's scared the council finds someone else living in the flat, they'll take it away from her. Won't let me turn the lights on, or answer the door after 10pm. Got to play like she's home asleep, and I's not there."

"Detective Inspector, really, I think we're done here."

"Miss…ah, Angel, you will remain in custody while we investigate further." Lestrade started to reach for the recording machine. "This interview terminated at…" the DI glanced at the clock on the wall, "…07.48."

Out in the hall, John caught up with Sherlock and Lestrade.

"You were right, Sherlock. Severe hypocalcemia. That's a calcium deficiency, Greg- severe enough to give her very fragile bones. Molly says cause of death was exsanguination, due to a shard of clavicle bone nicking the subclavian vein and the blood not clotting properly. The baby bled slowly to death."

"Did she say how the injury happened? Could it be a one off- kid won't stop crying, so the baby sitter pops her one?"

Sherlock glared at the DI. "No. I've seen the X-rays. This child likely had broken bones from birth. All the evidence could be the result of the baby trying to sit up in its cot and falling over. Those bones needed very little pressure to snap. Angel has told you that she did not touch the baby, and there is no evidence to show that she did. Sergeant Donovan has checked the cot for fingerprints, and there are none that match Angel's. If you let me ask the questions of the mother and father, then I will get corroboration. And do the decent thing, Lestrade, let John tell the parents together about their baby's condition and how it died. They deserve the truth."

Sammy and Nazir were being kept apart, but when they were brought into an interview room, both looked devastated. They hugged and Nazir spoke quietly to her in Arabic, trying to calm her distress.

John told them what the autopsy had found, and explained the underlying condition that had led to the baby's death. Lestrade stood listening through it all, and then stepped forward.

"I'm sorry I have to ask it, but I do. The young woman you left babysitting. Do you think there is any possibility that she could have hurt the baby in some way? Without meaning to, not knowing about the disease?"

Sammy was shocked. For the first time, she spoke, in halting English. "Wrong. That is …so wrong. Angel with me on the streets since she was thirteen years old. Kicked out of home by her junkie mother for getting pregnant. Angel never tell her mother that the father of the baby is stepfather. "She run away but got caught, because pregnant child too easy to find on streets. Social people make her go home, mother not believe her; took her stepfather's word as the truth and called her a liar- she get beat up by both of them, so bad. She run away again. The baby was born dead on the street, and she tried to turn it into a hospital so they'd look after it, but it was dead. When I got pregnant, she tells me that if I can't keep baby, she will take it. Never, never would she hurt my Masarah." And then the tears just rolled down her cheeks.

"She going to miss my poor Masarah as much as me. At least I have Nizar, maybe God will bless us with a second child. Angel has no one."

Sherlock intervened before Lestrade could ask anything more. "Let it be recorded that Sameh Ali Nasser and Nizar Al Husseini came in voluntarily to offer testimony to corroborate the suspect's statement, and to give evidence as to her character- despite the possible consequences for their personal situation. I would anticipate no charges being made against the suspect, and the witnesses here being released following a written statement. Does that match your reading of the situation, Detective Inspector?" There was challenge in Sherlock's tone, as if daring the DI to disagree.

Lestrade pursed his lips, and then shrugged. "Hard to see a prosecution case succeeding, so, yeah. We'll let her go."

They gave Sammy and Nazir some privacy, and Sally went to process the paperwork to release Angel.

Out in the corridor, Sherlock headed for the stairs, with John in tow.

"Sherlock; wait a minute," the DI called out.

"What?"

"The evidence all pointed in one direction. How did you know it was  _not_  child abuse?"

"You should have more faith, Lestrade. You ought to know by this time that when a fact appears to be opposed to a long train of deductions, it invariably proves to be capable of bearing some other interpretation.** In this case, hypocalcemia is a better interpretation than child abuse. It fits the profile of the injury better, and it doesn't make assumptions about the people who tried to care for the child in the only way they knew how." He turned to leave.

John saw that Lestrade had that  _you'd-better-explain-how-you-know-this_  look on his face, but John got in first with his own question. "How do you know so much about hypocalcaemia?"

Sherlock stopped, mid-swirl and turned back to look at the doctor. "I was two when I had a seizure. And the GP was smart enough to look beyond the obvious. He spotted the fact that I wasn't absorbing calcium properly. As a child, I disliked drinking milk, and calcium supplements didn't work. Eventually, logic overcame my taste buds."

The doctor gave him a wry smile. "Well, at least that's one mystery solved."

"What?"

"Why we're always running out of milk."

 

**Notes for the Chapter:**

> Part one:  
> *Shells are what Harrow calls the first year intake of pupils.  
> **Mrs Sue Allen was a real person- and quite an institution. She was matron of Bradbys House from 1983 to 2008. She was there when Benedict Cumberbatch attended!  
> *** The calcium paradox is an oddity. Calcium is essential for both neurotransmitter release and muscle contraction. From the presynaptic release of neurotransmitters, to the electrical mechanical coupling in the myocyte, almost every step in the neuromuscular function is predicated on calcium. Given these important physiological processes, it seems reasonable to assume that a calcium deficit (hypocalcemia) should lead to reduced neuromuscular excitability. Counterintuitively, however, clinical observation has frequently documented hypocalcemia's role in induction of seizures and general excitability processes such as muscle twitches, myocardial spasm and bronchospasms. Research continues to explore why this is the case.
> 
> Part Two:  
> *hypercalcemia is a challenging condition. The consequences can be quite severe. Severe symptoms of calcium deficiency disease include: insomnia, memory loss, muscle spasms, numbness and tingling in the hands, feet, and face; depression, hallucinations, even seizures. Calcium supplements (Calcium carbonate, Calcium citrate) are not organic calcium, so absorption can be surprisingly poor. I should know. I've had a calcium deficiency all my life, and hate drinking milk, and yes, I had a fit when I was two.
> 
> **ACD Canon- a direct quote from "A Study in Scarlet."


	3. Chapter 3

**Summary for the Chapter:**

> That calcium plays a role as activator of cardiac contraction was first suggested in 1883, when Sydney Ringer from Norwich observed that frog hearts placed in a calcium-free solution ceased to beat. This led to the development of Ringers solution, commonly used today in in vitro experiments on organs and tissues. But the questions of how calcium causes the muscle to contract, or how calcium is removed, allowing the muscle to relax, were not answered until the 1960s, when major discoveries were made in the areas of biochemistry and biophysics. The consequences are still widely misunderstood, especially when it comes to re-starting a heart that has stopped. Sherlock has known this from an early age.

**Notes for the Chapter:**

> The second half of this chapter addresses something odd. Ever since I saw The Great Game and heard Sherlock mention the shoes, I've been suspicious about his claim that he "read about it in the newspapers." The only way he'd know the shoes were missing was if he was there when it happened. This is me fixing a plothole in a Moffat/Gatiss script.

"What a mess…"

Detective Inspector Lestrade was fed up. The ambulance crew had been too late; the middle aged man was already dead by the time they got there. Now they were removing the body, strapped to the trolley. It looked bizarrely out of place in the company of the shopping carts being wheeled by the late-night customers in the Marks & Spencer Simply Food outlet.

This was not supposed to happen. Tom Harrison—the name of the person whose body was being carted off— was in a witness protection scheme. If he had still been alive, he should have been a crucial piece of evidence needed to prosecute the Waters Gang. As the Gang's bookkeeper, he knew just about every crime the north Hackney family had perpetrated over the past decade. Without his testimony, the Crown Prosecution Service would have to fall back on what was circumstantial evidence. And they'd proved before just how easy their lawyers could run circles around that kind of case.

DI Lestrade surveyed the wreckage in the aisle. According to eye-witnesses, the victim had staggered and fallen into the fresh vegetable racks. Onions and potatoes had scattered everywhere, and two shop workers were trying to sweep them up before someone fell on them.

DI Lestrade was frowning. Behind him, a constable was unreeling yellow and black tape to cordon off the crime scene.

"You're sure?  _Really_  sure this wasn't just a heart attack?" His questions were directed at a Consulting Detective who was pacing in agitation. Backwards and forwards, in front of the racks of salad vegetables, somehow managing to miss the onions that had rolled over to this side of the aisle.

"Of course, I'm sure. This is a murder, Lestrade. Look beyond the obvious.  _Why_  his heart stopped beating was more important. The autopsy will confirm it."

Another detective was talking quietly to one of the store staff, who was explaining, "I thought he had a heart attack…but the defibrillator didn't help. I followed the instructions; put the patches in the right place and everything. I must have done it wrong, it wouldn't shock and now he's dead. Why wouldn't it shock? Is it broken? If I'd shocked him then I could have saved him."

The young man in an M&S uniform looked forlornly at the discarded AED equipment lying on the floor- the opened box, the instruction card, the yellow battery pack. He was close to tears, devastated by his failure.

Sherlock snapped. "A defibrillator never works on asystole; any idiot knows that. The machine probably told you that; if you hadn't been panicking so much you would have heard it. If the heart's electrical activity has actually stopped, then no AED is going to work- the shock is only to get a proper rhythm going when the heart muscle is still beating. Were you doing CPR?"

The young man shook his head. "No, I'm not trained in that. Our first aider is on holiday this week. How was I supposed to know… what was that word you called it? A- syst something?"

Sherlock muttered, "Why is it that every idiot who watches crap TV thinks that dead bodies can be restored to life by a single shock? Scriptwriters are guilty of such stupidities, only outdone by the people who believe such drivel."

Greg scrubbed his hands across his chin, realising he had more than a five o'clock shadow. The long day had been spent trying to track down a phantom, who was now lying dead on the floor of the shop. Tom Harrison had done a runner that morning from the hotel room where he was sequestered, prior to his appearance tomorrow on the witness stand at the Old Bailey. The constable guarding his room had ushered in a hotel kitchen man carrying Harrison's breakfast tray, and then ended up on the floor of the bathroom, bound and gagged.

How a middle-aged, slightly overweight accountant with heart trouble could have knocked him out and then killed the man delivering the tray, Lestrade did not know. That's when he was called to the scene. Murder Investigation Teams didn't normally get involved in burglary cases- that was another area of the Homicide and Serious Crime Command. But, as this was the first time the Waters Gang had resorted to murder, he was on the case. And the first thing he did was call Sherlock.

"I'm not a sniffer dog, Lestrade. Get your missing persons people on the case."

"Sherlock, it's not the murder of the porter that I need you to solve, it's the one of the witness that I need you to help me  _prevent._  If they get their hands on Harrison, they will certainly do whatever it takes to shut him up permanently."

The Consulting Detective sounded peeved. "Witness protection seems to be an oxymoron in this case." There was a sniff. "Well, I suppose preventing a murder has novelty value. Text me the hotel address."

Greg had sent him the address:

**10.17 St Giles Hotel, Bedford Avenue, Camden, London, WC1B 3GH**

A minute later, the snarky reply came in.

**10.18 Budget cuts at Met? Downmarket, over the YMCA = death trap SH**

Greg grimaced at the truth in that statement. Harrison had been safely buried in the suburbs for the past five months, after producing just enough documentary evidence to get his immunity from prosecution. He had promised to "reveal all" once he was on the witness stand, but not before.

DI Simon Pelham of the Organised Crime team was in his late thirties, keen and eager with the youthful enthusiasm not yet jaded by years of exposure to crime. He made Greg feel old as he explained why Harrison had come to him as a potential informant seven months ago. "He'd found out he's got heart problems. He decided he had to get out of his stressful situation. Bookkeeping isn't usually considered a hazardous job, but clearly it is when you do it for the Waters Gang. Said he won't do this until he was sure we could lock up Guy Waters for good, and then only if we agreed to get him out of the UK. He said the rest of the Waters family won't rest until they've got his guts for garters."

According to Pelham, Harrison knew that it couldn't be a simple matter of going to his boss and saying he wanted to retire. He knew too much, and once he'd started working for them, Tom would not be allowed to leave. So, immunity from prosecution wasn't enough. If he was going to risk his life, he'd only give testimony in a court cleared of the public, with a guarantee of a new identity and fresh start overseas. "Wouldn't accept Spain; no way. According to Harrison, they've got more people in Marbella than Thomas Cook has. Took us two months to convince the CPS to bankroll the deal to move him to northwest Canada."

Moving Harrison to Central London for his day in court was always going to be risky, but DI Pelham told Lestrade that the CPS said the anonymity of the St Giles Hotel should have suited his star witness, and would make the transport by car to the Old Bailey a straightforward fifteen minute drive.

When Sherlock had arrived at the hotel room, he stopped in the room's foyer by the door to examine something on the wall—a mark that to Lestrade's eyes looked like just one of the many nicks and scuffs that dragging luggage on wheels would inflict on most hotel rooms.

The Consulting Detective ignored Lestrade's introduction of DI Pelham, and pulled out his pocket magnifier to look at one mark in more detail.

"This is a three star hotel, so no room service breakfast. But the Met paid the kitchen to deliver- thereby telling anyone who wanted to know that the room occupant was not a usual customer. You might as well have hung out a sign saying "key witness here". The kitchen staff member arrives, puts the tray on the table, and then came back to the door where the constable was waiting. But something he did made the officer suspicious. Then the kitchen man hits the officer with a cosh- made of hard rubber." Sherlock snapped the pocket magnifier shut. "That mark on the wall was made on the follow-through."

Pelham's eyes widened. "That's what PC Marston said when he regained consciousness; that's it  _exactly_."

Sherlock then looked over the white uniformed body lying in a pool of blood in front of the door to the bathroom. There was a dented electric kettle lying on its side in a damp patch on the floor a few feet away. Rolling his eyes, he snapped, "You don't need to be Einstein to figure out the cause of death in this case. Blunt force trauma to the side of the head, caused by being hit on the temple with a full kettle."

He checked the man's pockets, then stood up, stepped over the dead body and went straight into the white tiled room. Small but functional, it was now covered in the black powder of the Crime Scene Examiner, who was busy lifting fingerprints.

"Out."

Sherlock's imperious tone started the blue-suited dark-skinned forensic officer, who called out "Guv? What's he doing contaminating my crime scene?"

Pelham raised his eyebrows at Lestrade, who answered the man. "Just give him the room for a minute; his samples are all on file."

The man emerged wearing a disgruntled frown. "How do you expect me to do my job?"

"Just hold on a minute, Safik; he'll be out of your way soon enough."

Greg watched from the doorway. Sherlock's eyes were roving around the small room, before locking onto the rubbish bin under the basin. He tipped the contents onto the melamine counter-top, and poked his gloved hand through a wad of tissues and other detritus, including an empty and crushed foil packet.

"Hmm…. He's on Verapamil. Heart condition."

Greg had to step smartly back when Sherlock strode out of the room and back to the small closet by the hotel door.

As the Consulting Detective moved the sliding door to open the space wider, DI Pelham offered, "Harrison took his things- his clothes, a roll on bag, his washing kit, left nothing behind. That's why we think he bolted, rather than being kidnapped."

Sherlock rolled his eyes again. " _Of course_ , he's run. Your absconding witness assumes that as the gang wanted him dead, they'd do it here, as a way of thumbing their nose at police ineptitude. Maximise the publicity, to remind other people in their network of the folly of turning state's evidence. He's wrong, of course, but paranoia can lead to bad judgment."

He crouched down and used his pocket magnifier on the floor of the closet. "I assume you've circulated his photo? Got the CCTV crew trying to find him?"

Pelham nodded, "Of course."

"Well, tell them to look for someone wearing trainers and a hoodie."

The Organised Crime DI asked, "He didn't have anything like that with him."

There was a snort from inside the closet. "No, you idiot. He got it from the kitchen man's locker. The man's key is missing. If you wanted to leave the hotel without attracting attention of your killers, wouldn't  _you_  try to disguise yourself? You obviously didn't notice what the accountant saw - he's the same height as the porter."

Lestrade was amused. For once, it was nice not to be on the receiving end of Sherlock's scorn. He watched as Pelham struggled to keep up with the Consulting Detective.

"How do you know how tall he was? I haven't told you that."

A disembodied voice from the closet snapped, "It's obvious. Look at the wound on the porter's head. The kettle was used by a man who is 1.8 meters. It's a simple case of trajectory mathematics. And he wore a size 10 shoe, if the newest imprints in the carpet in here are anything to go by." Lestrade bent over the porter's body. His cheap black shoes had 44.5 inside a circle stamped on the rubber sole.

Then Sherlock came out of the closet and moved to the small round table that still held the untouched breakfast tray.

"How long has Harrison been staying here?"

"Checked him in yesterday morning. The CPS wanted the prosecuting team to rehearse him for today's testimony. When they left at five, he was fine."

Sherlock raised the little milk jug next the unopened packet of muesli sitting in the white bowl. He pulled the plastic wrap off the jug and brought it to his nose before taking a deep sniff.

Pelham looked startled, and cast a glance at Lestrade, as if seeking reassurance that Sherlock wasn't behaving oddly.

"And he had tea or coffee yesterday, didn't he? With milk."

Pelham shrugged. "I can ask the constable who was on duty; he's at the Charing Cross station getting the medical guy to look him over. Not used to being knocked on the head and tied up." The younger DI was frowning. "Why does it matter what he had to drink yesterday?"

Sherlock didn't answer, but took two steps to the bedside table and picked up the phone receiver, stabbing two of the numbers.

"Yes, this is Room 47. Put me through to your kitchen. Yes, I know you don't do room service, but just connect me- I need to ask about the menu."

There was a brief pause, then "Hello, this is Room 47. Someone in the kitchen sent stuff up here yesterday afternoon and last night. I'm not feeling well, and want to know if someone served me cow's milk instead of the soya milk I ordered. I'm allergic to it."

Lestrade and Pelham looked on as a knowing smile grew on Sherlock's face. Even from where he was standing Greg could hear an apologetic voice answering the question.

"Thank you. Good bye." He hung up and said to the CSE man, "Take that milk jug to your lab and test it. You'll find it's got as much as 10 grams of a sustained release calcium channel blocker medicine in it- probably the same one he's been taking for the past seven months. It's called Verapamil. The Waters Gang probably got this dead kitchen porter to deliver the same dose last night, in the milk he ordered along with his Americano decaffeinated coffee at 10 pm. That gives us less than twelve hours to find Harrison before it kills him."

The two DIs exchanged worried looks; Lestrade recovered first. "You think Harrison has been  _poisoned_?"

"Overdose of calcium channel blocker. They'd have found it easy to discover what medicine he's on. His local pharmacy where he first picked up the medication would be amenable to persuasion, if the Waters Gang is half as well connected in the local community as they should be—probably help the family with their illegal prescription drug business. And, yes, a massive calcium channel blocker overdose is highly likely to be lethal; there's no real antidote. Although the symptoms caused by accidental overdoses can be managed if someone gets to an Emergency Department, it has to be  _early_. But, in this case, because he has no idea that he's actually taken it, he won't seek help when it could actually make a difference. By the time he comes to decide that he's feeling so unwell that he'll risk coming out of hiding to go to a hospital, it will be too late."

Sherlock pointed to the milk jug, still on the tray. "Verapamil is a sustained release drug. Once a day- so presumably when he took his usual dose this morning, he will have added fuel to last night's fire, having received a hefty dose in the milk. Just to be sure, the kitchen porter would have included an even bigger dose in this morning's milk, just to hasten things along. Your constable must have become suspicious about the man, and then Harrison just took things into his own hands."

Pelham looked down at the dead body. "How could a middle-aged accountant manage to kill him?"

"Fear is a blunt-edged instrument, Detective Inspector. Once he realised the porter was a Waters Gang member, he'd do whatever he had to in order to survive. When the kitchen porter was knocking the constable out, Harrison would know he was next. You'll find his finger prints on the kettle— and blood traces, if your CSE can be bothered to look in the right direction instead of wasting everyone's time putting fingerprint powder all over the bathroom."

Lestrade stepped forward. "All that is kind of after the fact, Sherlock. Where do you think we're going to find him? Harrison is the man I need to focus on. Not only is he a suspect in this murder case, but if the Waters Gang catch up with him first, then we'll have a second murder on our hands."

Sherlock looked at Lestrade with scorn. "Not necessary. The Waters Gang has already 'murdered' your witness. He's a walking time-bomb, due to go off in the next twenty hours. Think of him as a dead man, walking."

Now it was Pelham's turn. "If we can find him and get him medical help, then surely he can be saved. Killing the kitchen porter can be treated as self-defence. He can still testify."

Sherlock just laughed. "What part of "no antidote' do you not understand? Verapamil is a non-dihydropyridine calcium channel blocker; it depresses atrioventricular nodal conduction. Symptoms include dysrhythmias, hypotension and bradycardia- all of which could be managed if he were in a hospital bed shortly after consuming the overdose. But he won't be, because he's scared witless of being killed. To our knowledge, the Waters Gang has never murdered anyone yet, and they don't want to be implicated in this one. Quite clever of them, medical treatment, if your witness doesn't die of heart failure first, then bowel infarction, renal failure, stroke, or non-cardiogenic pulmonary oedema might be the cause of death. "

"So, how do we find him?"

"Think about it. If you wanted a hide-away, where no one would think of looking for you, where would you go?" The brunet looked expectantly at the two Detective Inspectors.

Lestrade shrugged; Pelham opened his hands in surrender. "London's a big place."

Another eye roll. "Oh, for God's sake, use your tiny little minds. He's already rifled through this man's locker. What's he going to find in there other than his clothes? A wallet perhaps? With identification and an address? Flat keys? A place to hide that the Waters Gang has no idea about?"

This time it was Lestrade who said, " _Oh!"_

Six hours and twenty minutes later, they were in Ruislip, walking down a litter strewn alleyway behind the high street. It had taken them  _forever_  to track down the porter's home address. First of all, the St Giles hotel didn't have the man on their own books- he was agency staff and had only started working there two days ago. It took him another twenty minutes to figure out which of the three agencies the man had come from. No, he didn't actually know the bloke's name- just gave him the badge that said Taylor. "Our female guests want the staff to wear badges, so they do. No one says it has to be their real name. We can't be expected to produce a new badge for every Tom, Dick or Harry that the agencies send us."

It took the St Giles manager three phone calls to connect with someone at the agency; the first two numbers just dumped to an answer machine. And even when he did get through to a real person, that person clearly didn't want to divulge information about an employee of theirs.

It took all of two minutes once Sherlock had grabbed the phone out of the manager's hand and spouted in some Eastern European language to come up with a name- but no address, alas.

"Demetri Perjan. Moldovan national. Not legal. Probably came in on a Romanian EU document."

Pelham was impressed. "How did you get them to give you the name?"

"I threatened him with divulging to the two police detectives standing here with me the fact that his agency was a front for a gang master providing work to illegals, unless he gave me the name of the porter he'd placed here two days ago."

Lestrade smirked. "You are wicked, Sherlock." Pelham was frantically writing something down in his notebook.

"So, we have a name. What happens next?"

"I disappear. The next people I talk to won't want to be seen speaking in front of police officers. I'll call you when I get a trace."

It took four more hours before Lestrade's phone finally peeped.

**18.48 Meet up Red Onion Café. 95 High St, Ruislip HA4 8JB SH**

Forty minutes later, Lestrade and Pelham walked into the café and were introduced by Sherlock to the estate agent from Austin's.

"This is Jason White; his agency was mentioned to me as finding Perjan a flat in the area. But he won't tell me where, even though I have told him a man's life depends on it."

The young man had been eyeing Sherlock suspiciously, but was more reassured when both Lestrade and Pelham pulled out their warrant cards.

"I don't want any trouble, and I don't want to get my clients into trouble either."

Sherlock rolled his eyes. "Your  _client_  is dead. It's his murderer we're after- we think he took Perjan's keys. Just face facts—you're supposed to check whether your rental clients have proper ID and the right to be in the country, but you just couldn't be bothered."

The young man almost cringed. "He had papers; how the hell am I supposed to know if they are valid or not?"

Lestrade stepped in. "Look, son. We're not after you, and the issue is irrelevant, because Perjan is dead. But, I really need you to tell us where the flat is."

White started to nod. "I've brought keys; I can turn them over to the  _proper_  police." The he pointed up at the ceiling toward the back of the café. "Only the one studio flat up there- not re-furbished. Weekly rental- no long term contract, no deposit. No one wants to live overtop a café's kitchen. Smelly, noisy and going until midnight, it seems. Entrance is in the back- get there down the alley, which also makes it hard to find anyone willing to take it. And the view leaves something to be desired."

That was an understatement that only a London Estate Agent could make, in Lestrade's opinion, as he walked down the litter-strewn alley. The flats over the shops would be noisy, but at least they had windows onto something more pleasant than tumbled down and graffiti- covered concrete garages with rusting, corrugated iron roofs. Perjan's flat was probably a borderline squat in truth.

The younger DI led the way, with Lestrade and Sherlock behind, up the steep staircase to the door at the top. He banged on the door, and called out, "Open up, Harrison. We know you're in there. This is DI Pelham; we're here to take you back into protective custody."

There was an ominous silence. Pelham used the estate agent's keys. Fortunately, the dead bolt had not been turned, so they could get in.

The tiny flat was empty.

Very sparsely furnished, the room was scanned by Sherlock in the seconds it took him to pull on his forensic gloves before he went diving into the even tinier bathroom.

"Someone's been here since Perjan left this morning, and it's most likely Harrison."

DI Pelham poked his head into the frankly disgusting WC. The toilet bowl was badly rust stained. "How can you tell?"

"Scent…"

"What do you mean?"

"Whoever had a pee here last missed the bowl, and the lino is still damp. Sort of thing that someone feeling faint, dizzy and weak would do." He rubbed two gloved wet fingers together under his nose. "Urine scents tell you a lot about the health of the person who peed. And this is not good." He waved his fingers at Pelham. "Sweetness means he's hyperglycaemic; his kidneys can't rid his blood of glucose. One of the symptoms is a frequent need to urinate. It also means that he's started renal failure."

Outside the tiny room, Lestrade grimaced. "How much longer do you think he's got?"

Sherlock shrugged. "Not long. To be honest, I thought we'd find him dead on the floor in here."

Somewhere up the high street, a siren began to wail, strengthening in volume as it came closer.

Lestrade and Pelham must have been inured to the sound, and just filtered it out. Sherlock, however, stood up. "If he's hyperglycaemic, he should feel intensely thirsty. Anything in the fridge out there, Lestrade?"

A quick look showed an empty fridge, while Sherlock turned the tap on over the tiny steel sink in the kitchen corner of the flat. It ran a thin dribble of rusty brown water.

"He got thirsty- and couldn't face drinking this. Follow that ambulance siren, and we might find out where he went."

The trail led them to the Marks & Spencer  _Simply Food_  shop- three hundred feet down the high street from the Red Onion—and to the dead body on the floor amidst the onions and potatoes.

"You're sure?  _Really_  sure this wasn't just a heart attack?"

"Of course, I'm sure. This is a murder, Lestrade. Look beyond the obvious.  _Why_  his heart stopped was the more important fact. The autopsy will confirm it."

Sherlock stopped pacing and put his hands in his pockets. "Massive verapamil overdose, ingestion of greater than 8 g, is almost uniformly fatal with few case reports of survivors unless they sought treatment." He glared at the shop assistant. "Stop snivelling; it wasn't your fault. You didn't give him the calcium channel blockers. It's not your fault that there was no electrical differential that could react to the defibrillator. If you attempt to shock a heart in asystole, the machine won't let you. It's basic chemistry. There are no electrolytes to force out of the cells that are any different than the ones that are already outside the cells, so you can't create a muscle contraction. Even if you could have over-ridden the safety features, all you'd get is heat- in effect, you'd have cooked his heart. And the machine won't let you do that. No, what you should have been doing is CPR."

The young man choked off a sob and ran.

DI Pelham winced. "You know, you are a cold-hearted bastard, Holmes. That poor kid won't ever be the same after that little lecture."

Sherlock narrowed his eyes. "I'm just telling the truth, Detective Inspector. Doing my bit to counter-balance all the stupidities perpetrated by bad scriptwriting."

Lestrade shook his head. "Knowing all this doesn't help, Sherlock. What matters is that those bloody bastards in the Waters Gang are going to get away with it again. The court case will get dismissed tomorrow."

"Oh, just use your imagination, Lestrade. Set them up, bait them with a big enough prize, hack their computers and just catch them red-handed. It's what I would do, if I were you." He turned on his heel and left the crime scene.

Greg thought about it. Unorthodox for sure, but it might just work. He wondered if DI Pelham would be up for it.

oOo

"Why can't I go swimming today?" It was a simple question, but the ten year old who asked it in a fierce voice did not appear to be in the mood to hear the reason. In fact, he looked utterly outraged. "Tell them to leave, now."

Terry Stephens tried to find some patience from somewhere. This particular  _customer_ — yes, he had to remind himself of that fact—was not only a regular, but someone whose family paid a great deal to have him receive private swimming lessons, in a pool empty of other children. And it had to be Tuesdays at exactly the same time: 2.15pm.

Normally, Stephens didn't mind. The Queen Mother Sports Centre on Vauxhall Road was almost always empty at that hour anyway. There were three pools in the Westminster Council funded centre. In the main pool, the morning "rush hour" was over- the working people who wanted to swim laps between six and eight before work were gone. Then the aging ladies took over his attention in the leisure pool who liked to pretend that they were getting their exercise at the aquarobics class at 11.15, when in truth what they wanted was an excuse to have a coffee and cake next door at the café, without feeling guilty about it. The lunchbreak brought in some people who were willing to sacrifice a meal for a few quick laps. Then there was the mother and toddler session to supervise in the smaller teaching pool at one. After the school kids were let out at three o'clock then he was on life guard duty because all three pools would be heaving until five thirty, when the after work crowd came in and kept the lanes moving until the main pool closed at nine. His evenings were spent in the leisure pool area, coaching the water polo teams and then various fitness sessions.

So, 2.15 to 2.45 was the allotted time for his private lesson with the ten year old, who was glaring fiercely at him. When the Viscountess of Sherrinford had proposed private lessons when the boy was six years old, Terry had been happy to agree, especially when she explained that the child was being home-schooled and would be able to come at whatever time suited him, so long as the pool was otherwise quiet. She had paid an extortionate amount, on the condition that her son had his undivided attention. The lad had sensory "issues", as she described it. "He needs to be  _drown-proofed_ ; Parham has three ponds, and he is now getting quite adept at escaping his nannies. But he won't tolerate other children so private means private. We are in London for most of October, February and March, and will give you advance notice of other times." She'd given him a lovely smile. "I know it is asking a lot, but in return I am happy to sponsor one of the disability sessions so you can offer your classes for free to anyone in the borough who would benefit. Just present the bill and it will be paid."

Stephens was a certified Swimming for Confidence instructor, used to working with disabled children. One of the problems for the families was the fact that they couldn't get their pool fees waived. On an income already stretched by the demands of a disabled child's health needs, leisure was always bottom of the list. The Viscountess's generosity would be a huge benefit.

Over the past four years, Stephens had come to terms with the boy's sensory issues, and he'd found a way to get Sherlock Holmes to focus on learning how to swim, and then to improve his skills. But, the boy needed to follow set routines to be comfortable. He'd just started working with him in the main pool, developing his endurance and stroke fluency. Taking two of the lanes out of adult usage for the half hour was not a problem.

Right now, however, that was far from possible. Because the noise in the pool area was deafening, Sherlock would not meet his eyes and the anxiety poured off of him. Stephens knew that getting cross at the boy because of the mix-up was not going to help.

"I told you last week—there's a swim meet today between the Year Six teams at Brighton College, Westminster School and Blackrock College from Dublin. You were supposed to tell your…" here Stephens had to stop himself from saying  _your mother_  because the swimming instructor remembered that the boy no longer had one. She'd died the previous January. Then he was told that the boy was away. It wasn't until September when the swimming lessons resumed, someone from the Viscountess's London townhouse delivered the boy every Tuesday afternoon at just after 2pm. On this occasion, however, because Stephens would be occupied with the competition, "You were supposed to tell the person who brings you that you were not to come today," the tall muscular coach finished rather firmly.

Sherlock had showed up as usual, carrying his swimming kit bag, and been stunned to find the swimming pool area crammed with boys—dozens of them, all in bathing suits, sitting in the gallery stands above the pool, shouting at the six swimmers who were in the middle of a race. The noise in the indoor area was overwhelming- fifty two under twelve boys at full throttle, and it made Terry flinch, so God knows what it must be doing to the boy.

Glancing around, he figured he had about four minutes before the end of this one and the start of the next race. Putting his clipboard under his arm, he steered Sherlock into the locker room where it was quieter.

"Do you think the person who brought you might still be here?"

The boy had retreated into silence. But he shook his head.

Stephens sighed. He probably had a contact phone number for the boy's carers somewhere in the files in his office, but getting it and then calling would take him even longer. By the time the person got there to collect Sherlock, most of the half hour allotted for the swimming lesson would have passed anyway. The best thing to do would be to keep the boy here and let him be collected as normal. What he couldn't do is let Sherlock loose on his own in either the leisure pool or the training pool. Supervision in the water was essential.

"Right. This is what is going to happen. You can't have a lesson today because the pool is being used and I have to be here to manage the meet. You can watch the races from the upper gallery; would you like that? You could learn from the other swimmers. These kids are the best in their school, and the winners of these races get to go onto compete next month for the London school finals."

Sherlock was looking back through the double doors toward the pool, where the noise started to reach a crescendo of yells and calls, encouraging the competitors in what must be the last lap. Stephens watched him flinch as the roar burst into cheers. The boy shook his head fiercely.

"Then you will have to stay here in the locker room. Promise me you are going to sit right here and not move until I come to get you. I can't keep an eye on you; I have to run the next race—the 400 meter freestyle. Will you be alright in here?"

Stephens needed to get back to the swimming hall. He took the boy's nod at face value, and left him sitting on the bench that ran between the two rows of lockers.

By the time the next six competitors were lined up on the starting blocks, he'd re-focused on the management of the meet. The older boys from the three schools who were serving as timekeepers were ready, stopwatches in their hands for the lane they were marshalling. Stephens gave the sharp blast on the whistle that set the six boys diving into the water.

By the third of eight laps, the boy in the fourth lane was powering ahead of the others. He was taller, bigger shouldered than his peers, and it looked like Brighton College had a real winner on their team.

The boys in navy blue swimming trunks down the left side of the pool were all shouting out encouragement to their two competitors, while on the right the Blackrock School pupils were looking a little down-hearted. As the home team, the Westminster Reds were at the far end, shouting their heads off as their two came to the turns.

Stephens had to be impartial but it was hard; he knew the swimmers from Westminster. By the fifth lap, the fourth lane Brighton boy was slowing down —probably sprinted too soon in the race and was now struggling, his freestyle stroke was losing fluidity. The leader of the Blackrock boys over in the seventh lane caught up and at the turn came off the wall in a really smooth manoeuver, followed closely by a swimmer Terry knew to be a strong finisher. The boys on the Westminster side of the gallery erupted into cheers and shouts, egging on their team mate to greater effort.

By the start of the eighth lap, all of the boys were bunched together- only a stroke or two separated the lot. It was going to be a close finish. The noise was amazing as all three teams were shouting at the top of their lungs. In a final flurry of splashing, Stephens lined himself up at the finishing wall on the high chair to be sure to see which boy touched first.

Lane Seven was the winner, but only by the narrowest of margins over Lane Two, followed in close succession by lanes six and one. The cheers that went up from the gallery shook the rafters.

Stephens came down off the chair to confer with the timekeepers- it had to be an agreed win by all three schools. Luckily despite the racket, he got the nods he needed from the sixth form boys serving as marshals, and marked the victory onto the clipboard.

Then something in the pool caught his eye. Not at the end where the boys were clambering out of their lanes, but rather something dark at the bottom about half way down the pool. Stephens walked down the side, and then realised through the rippling water that it was a swimmer.

On the bottom. Not moving.

He shouted to the timekeepers, threw down the clipboard and kicked off his shoes before diving into the water.

The next few minutes passed in a blur, as Stephens lifted the dead weight from the bottom of the pool and his training kicked in. Coming to the surface, he used a lock hold across the boy's chest and kept his lolling head above the surface. A few savage kicks and he was at the side, where arms reached in and grabbed the boy to pull him from the pool.

As Stephens hauled himself out of the pool, he realised that the joyful shouting had stopped. The boys were milling about in stunned silence, shocked and scared. One of the Brighton school PE instructors was down on his knees beside the boy, already giving mouth-to-mouth resuscitation. The Blackrock College instructor was steering the other boys away from the side of the pool away from them.

"I'll call the ambulance from the office." Stephens dashed through the double doors, down the corridor that led to his office, next to the changing rooms. As he came through the office door at speed, he reached for the phone, repeatedly stabbing the 9 button.

"What service, please?"

"Ambulance…" Dripping water from his shorts and shirt, Stephens caught his breath as the dispatcher put him through to the service.

"Hello. Ambulance service. What is the nature of your emergency?"

"There's been an incident at The Queen Mother Leisure Centre, 232 Vauxhall Road, SW1. A boy was found unconscious at the bottom of the pool."

"Can you describe the state of the victim? Is he breathing?"

"No. I've left a colleague giving mouth-to-mouth."

"Is anyone trained in CPR?"

"Yes…several of us."

"Good. Keep using CPR with both chest compressions and rescue breaths. An ambulance is on its way; should be with you in about eight minutes."

As Stephens put the phone down, he turned and realised that he was not alone. Sherlock Holmes was sitting on the chair by the door; the swimming instructor had been in such a hurry when he ran in that he'd not seen the boy. "What are you doing in here?"

Wide-eyed, the boy ignored the question and asked one of his own, "Has someone drowned?"

Stephens gave him a pained smile. "Hope not."

"Can I come watch?"

"No."

The ten year old looked serious. "I've been taught first aid and CPR…at least in theory. Never had the chance to do it for real on a real live, drowned person."

For a moment, Stephens was nonplussed; instead of fear or worry, the boy's detached and curious reaction was different from what he might have expected from a ten year old confronted by a drowning victim.

He shook his head. "No, we've got plenty of trained help. You stay here. In a minute the rest of the boys are going to be going into the changing rooms. The race meet is over." He grabbed a pile of rolled towels from the shelf beside his desk and left in a hurry, not noticing that Sherlock followed him out.

At the other end of the corridor, the boys from the bleachers were being shepherded into the changing rooms by a couple of the school instructors. Over the murmuring voices of the pupils, the teachers' louder voices carried down the hall. "Just get changed and collect your things. Stay in the locker rooms until we tell you that it's okay to leave to get on the buses."

At pool side, the instructor from Westminster School had taken over from the Brighton College man, allowing the other teacher a chance to catch his breath. Stephens draped the dry towels over the still figure of the boy. "We need to keep him warm. Any progress?"

The Brighton man bit his lip and shook his head, then asked, "How long before the ambulance gets here?"

"Not long."

Stephens knelt and tried to find a pulse, before sighing.

"I'll help. You do the compressions; I'll do the breathing." For a few minutes, there was only the sound of quickly counted thirty compressions, two each second, which were then followed by Stephens giving two breaths. Pinching the boy's nostrils shut, Stephens delivered air into the boy, watching with his peripheral vision to see his chest expand fully. Then he released, and turned his head to feel the air expelled against his wet cheek, hoping that the boy would then inhale of his own accord. When he didn't, Stephens repeated the manoeuvre, before sitting up and letting the other life-saver begin the compressions again.

They heard the ambulance coming up the road and then stop out front. Then two uniformed paramedics came into the pool area and took over from the teachers. When he stood up, Stephens was a bit lightheaded, but saw that they had an audience. Standing quietly by the door, Sherlock Holmes was watching intently.

Stephens' pent up adrenaline and anxiety about what was happening spilled out into intense annoyance. He marched over to the boy and leaned down to growl, "I told you to stay in the office. This is not some stupid TV programme for you to watch.  _Get out of here!"_

Instead of being scared by the menacing tone of the adult, the boy did not look away from the scene. "They're going to intubate him. Use a tube to open his airway and then squeeze air into his lungs. I read about this. They'll try to use drugs to stimulate his heart; if they can get a pulse, then they might shock him to get a stable rhythm. There's a defibrillator box in the main reception. Should I go get it?"

Whatever Stephens might have said to this, his attention was dragged away by the paramedics.

"Need answers to some questions. How long was he under the water?"

The pool manager thought back to the last time he'd seen the occupant of Lane Four swimming, and then how long after the race finished. "I can't be certain. But I saw him on the surface last about five minutes from when I saw him on the bottom, after the race was over."

"Did he look like he was in trouble? Could he have hurt his head? Does anyone know if he suffered from epilepsy, could he have had a seizure?"

The Brighton instructor shook his head. "Nothing like that. He's our best swimmer- won the Southern Home Counties championship last year. And there was no contact with any of the other boys swimming; they were all in their own lanes. Why don't you shock his heart? Didn't you bring a defibrillator?"

The paramedic who was counting compressions shook his head. "Without a pulse, there is nothing to shock. You've been watching too much  _Casualty_. Bane of our existence, that bloody programme.*"

"What's his name?"

"Carl Powers. He's just had his eleventh birthday, three days ago. I can call the College and get his parents' contact details."

"Do you know if he was on any medication?"

"Not that I'm aware of."

"I'll check his locker and find out."

The fact that this was said by a ten year old, who then bolted through the doors and down the corridor startled several of the men.

The Brighton coach asked Stephens, "How does that boy know which locker belongs to Powers? And how will he get it open? He won't know the combination that Powers will have chosen."

Stephens asked those very same questions as he and Sherlock went through the locker. He was going through the blazer's pockets while Sherlock hauled out the kit bag and was rummaging around in it.

"I was sitting here. You told me to stay in the locker room, so I did. Then this boy—the one who's drowned— came in and got something out of his locker. He didn't say anything to me; just ignored me. But I saw him open the combination lock, so I know the numbers he used. 18-3-78. His birthday, obviously. He got a tube of something out of the bag and rubbed stuff on his fingers." Sherlock mimicked the action, spreading an imaginary ointment in the webbing between his fingers. "When he shut the door, his trainer lace got stuck and he opened it again, and very carefully put it back in, before locking up."

"Nothing here," muttered Stephens. "Find anything?"

Sherlock shook his head. "No medicine bottles, and no tube of cream." The boy was staring into the locker. "Where are his shoes? The trainers. They were there when he locked up."

Stephens went over to the bench and tipped out the whole contents of the gym bag onto the floor. "You're right. No medicine."

He stuffed all the kit back into the bag, and then put the boy's clothes in, too. Zipping it up, Stephens slung it over his shoulder and ran back to the pool side. The paramedics were putting the unconscious boy onto a trolley, still giving compressions.

"No medicine that I could find, but he may have had some sort of topical cream on his hands. Here's his stuff."

They were rolling the trolley now through the doors of the pool and into the corridor.

The Brighton teacher asked, "Where are you taking him?"

"St Thomas' A&E. Contact his family and get them to telephone. And wait here—the police will be here any minute."

Stephens' face must have shown his dismay. "Why?"

"Police are always called in the death of a minor."

"He's not dead yet," the Brighton instructor blurted out.

The paramedic who was astride the trolley administering compressions panted out, "There's always a chance, but only twenty percent of people who arrest completely ever recover…even the fit and healthy ones." The other paramedic who was pushing the trolley shook his head sadly. "When somebody's heart stops, it's normally done so for a good reason and it's unlikely we'll get it started again."

As they went out the door, a police car pulled up onto the pavement, alongside the ambulance. Stephens realised that they still had an audience, and he turned around to confront the boy.

"Sherlock Holmes, sit down here. Do not move from here until your ride arrives. I've got to sort out all the rest of the boys, and deal with the police when they come. I don't have time to think about you now."

"Should I come back next week at the proper time?"

Stephens gave a rather distracted nod, before heading out the door to meet the police officer.

Ten minutes later, Sherlock was still thinking it through—the sequence of events from watching the tall boy with the big feet come in, open his locker and leave, without a backward glance. Had he taken the cream with him? Sherlock couldn't be sure. He was certain that the shoes were still in the locker when he left the changing room to go to the office. He'd been bored, and wondered whether there might be something to read there.

"Ready to go?"

He looked up and saw Miss Forester, the housekeeper of the London townhouse.

Once they were in the back of the Bentley and heading back toward South Eaton Place, she looked over at him curiously.

"Sherlock, why isn't your hair wet?"

"Didn't go swimming today."

"Oh? Then what were you doing?"

"Something much more interesting. A boy drowned, and there is something not right, I have to figure it out. It's a puzzle."

He watched through his peripheral vision as the woman lifted her hand toward her face, clearly shocked.

"Oh, how awful! I am so sorry."

"Why? Why are  _you_  sorry? You didn't have anything to do with it. The question is, who did?"

She had a look on her face which his mother had told him was sadness. He didn't understand why. She didn't know the boy, had not been there, so why should she care? He'd watched the police come in, and wondered if anyone would tell them about the missing trainers. It was all very peculiar. How had they vanished between the time when he left the locker room to go into the office and then returning with his instructor? Who would have known the padlock combination? Why had the tube of cream been stolen along with the shoes?

Miss Forester was talking again. "I'm sorry that you had to witness such a horrible thing. I just feel so sorry for his family, too. You mustn't be upset. Accidents happen."

"It wasn't an accident. Someone did this, and stole his shoes. I need to tell the police."

"Sherlock, I don't think that this is something that you should even think about again. Whatever happened to that poor unfortunate boy, it's up to the authorities to sort out. We're going straight onto Grosvenor Gardens. Your chemistry tutor's session at the Abbey College starts at three, so we don't have any time to waste."

"But this is  _important._ "

"So is your education, young man. Your brother has arranged these lab sessions because you complained that your tutor at Parham was boring. At the college, you have the facilities and the private instruction that is way above your age level. Mustn't waste the opportunity. So that's enough talk about the incident at the pool. Put it out of your mind."

She said that as if such a thing were possible. For Sherlock, it wasn't. A bit like an experiment, he'd have to see if time would make a difference. After all, the boy might not die. The ambulance person had said there was a twenty percent chance of him surviving. He told himself that he would just have to wait until next week, when he could ask Mister Stephens if he'd told the police about the missing shoes. There were many more facts he needed to know before this puzzle could be solved.

Good chemists are patient, he told himself.  _I can wait._

**Notes for the Chapter:**

> * Casualty is an A&E drama produced by the BBC that has been running for thirty years. Way before ER in America, it covers the life and death dramas of an emergency department. However, television writers are not doctors, and they perpetuate too many myths and mistakes about how treatments take place. Don't believe everything you see on TV, in the cinema or read in Fanfiction. I must thank my medical betas, Kate221b and J_Baillier, for their professional advice.

**Author's Note:**

> ** This is a "missing Wednesday" story- and I had help on the anaesthetic work involved, from J_Baillier.  
> *** Mycroft always has a list!  
> ****Ted Bundy is REAL- the most extraordinary serial killer in US history, and makes Hannibal Lecter look tame.


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